REGTESTS: Replace REQUIRE_BINARIES with 'command -v'

This migrates the tests to the native `feature cmd` functionality of VTest.
diff --git a/reg-tests/mcli/mcli_start_progs.vtc b/reg-tests/mcli/mcli_start_progs.vtc
index 08de157..eb6f635 100644
--- a/reg-tests/mcli/mcli_start_progs.vtc
+++ b/reg-tests/mcli/mcli_start_progs.vtc
@@ -1,7 +1,7 @@
 varnishtest "Try to start a master CLI with 2 programs"
 #REGTEST_TYPE=bug
 #REQUIRE_VERSION=2.0
-#REQUIRE_BINARIES=sleep
+feature cmd "command -v sleep"
 
 feature ignore_unknown_macro
 
diff --git a/reg-tests/ssl/add_ssl_crt-list.vtc b/reg-tests/ssl/add_ssl_crt-list.vtc
index ca52285..7aae233 100644
--- a/reg-tests/ssl/add_ssl_crt-list.vtc
+++ b/reg-tests/ssl/add_ssl_crt-list.vtc
@@ -13,7 +13,7 @@
 varnishtest "Test the 'add ssl crt-list' feature of the CLI"
 #REQUIRE_VERSION=2.2
 #REQUIRE_OPTIONS=OPENSSL
-#REQUIRE_BINARIES=socat
+feature cmd "command -v socat"
 feature ignore_unknown_macro
 
 server s1 -repeat 2 {
diff --git a/reg-tests/ssl/new_del_ssl_cafile.vtc b/reg-tests/ssl/new_del_ssl_cafile.vtc
index 536db50..1b5bef1 100644
--- a/reg-tests/ssl/new_del_ssl_cafile.vtc
+++ b/reg-tests/ssl/new_del_ssl_cafile.vtc
@@ -11,7 +11,7 @@
 varnishtest "Test the 'new ssl ca-file' and 'del ssl ca-file' commands of the CLI"
 feature cmd "$HAPROXY_PROGRAM -cc 'version_atleast(2.5-dev0)'"
 feature cmd "$HAPROXY_PROGRAM -cc 'feature(OPENSSL)'"
-#REQUIRE_BINARIES=socat
+feature cmd "command -v socat"
 feature ignore_unknown_macro
 
 server s1 -repeat 2 {
diff --git a/reg-tests/ssl/new_del_ssl_crlfile.vtc b/reg-tests/ssl/new_del_ssl_crlfile.vtc
index eeed09c..54bbdc2 100644
--- a/reg-tests/ssl/new_del_ssl_crlfile.vtc
+++ b/reg-tests/ssl/new_del_ssl_crlfile.vtc
@@ -11,7 +11,7 @@
 varnishtest "Test the 'new ssl crl-file' and 'del ssl crl-file' commands of the CLI"
 feature cmd "$HAPROXY_PROGRAM -cc 'version_atleast(2.5-dev0)'"
 feature cmd "$HAPROXY_PROGRAM -cc 'feature(OPENSSL)'"
-#REQUIRE_BINARIES=socat
+feature cmd "command -v socat"
 feature ignore_unknown_macro
 
 server s1 -repeat 3 {
diff --git a/reg-tests/ssl/set_ssl_cafile.vtc b/reg-tests/ssl/set_ssl_cafile.vtc
index 5dcfaf9..72ce3e6 100644
--- a/reg-tests/ssl/set_ssl_cafile.vtc
+++ b/reg-tests/ssl/set_ssl_cafile.vtc
@@ -17,7 +17,7 @@
 varnishtest "Test the 'set ssl ca-file' feature of the CLI"
 feature cmd "$HAPROXY_PROGRAM -cc 'version_atleast(2.5-dev0)'"
 feature cmd "$HAPROXY_PROGRAM -cc 'feature(OPENSSL)'"
-#REQUIRE_BINARIES=socat
+feature cmd "command -v socat"
 feature ignore_unknown_macro
 
 server s1 -repeat 4 {
diff --git a/reg-tests/ssl/set_ssl_cert.vtc b/reg-tests/ssl/set_ssl_cert.vtc
index c4d0883..85684bc 100644
--- a/reg-tests/ssl/set_ssl_cert.vtc
+++ b/reg-tests/ssl/set_ssl_cert.vtc
@@ -22,7 +22,7 @@
 varnishtest "Test the 'set ssl cert' feature of the CLI"
 #REQUIRE_VERSION=2.2
 #REQUIRE_OPTIONS=OPENSSL
-#REQUIRE_BINARIES=socat
+feature cmd "command -v socat"
 feature ignore_unknown_macro
 
 server s1 -repeat 9 {
diff --git a/reg-tests/ssl/set_ssl_cert_bundle.vtc b/reg-tests/ssl/set_ssl_cert_bundle.vtc
index aaec89d..218f7bf 100644
--- a/reg-tests/ssl/set_ssl_cert_bundle.vtc
+++ b/reg-tests/ssl/set_ssl_cert_bundle.vtc
@@ -17,7 +17,7 @@
 varnishtest "Test the 'set ssl cert' feature of the CLI with bundles"
 #REQUIRE_VERSION=2.3
 #REQUIRE_OPTIONS=OPENSSL
-#REQUIRE_BINARIES=socat
+feature cmd "command -v socat"
 feature ignore_unknown_macro
 
 server s1 -repeat 9 {
diff --git a/reg-tests/ssl/set_ssl_cert_noext.vtc b/reg-tests/ssl/set_ssl_cert_noext.vtc
index f1c42ff..b7bafa8 100644
--- a/reg-tests/ssl/set_ssl_cert_noext.vtc
+++ b/reg-tests/ssl/set_ssl_cert_noext.vtc
@@ -14,7 +14,7 @@
 varnishtest "Test the 'set ssl cert' feature of the CLI with separate key and crt"
 #REQUIRE_VERSION=2.2
 #REQUIRE_OPTIONS=OPENSSL
-#REQUIRE_BINARIES=socat
+feature cmd "command -v socat"
 feature ignore_unknown_macro
 
 server s1 -repeat 3 {
diff --git a/reg-tests/ssl/set_ssl_crlfile.vtc b/reg-tests/ssl/set_ssl_crlfile.vtc
index 4ee7c12..f6d97ce 100644
--- a/reg-tests/ssl/set_ssl_crlfile.vtc
+++ b/reg-tests/ssl/set_ssl_crlfile.vtc
@@ -20,7 +20,7 @@
 varnishtest "Test the 'set ssl crl-file' feature of the CLI"
 feature cmd "$HAPROXY_PROGRAM -cc 'version_atleast(2.5-dev0)'"
 feature cmd "$HAPROXY_PROGRAM -cc 'feature(OPENSSL)'"
-#REQUIRE_BINARIES=socat
+feature cmd "command -v socat"
 feature ignore_unknown_macro
 
 server s1 -repeat 4 {
diff --git a/reg-tests/ssl/set_ssl_server_cert.vtc b/reg-tests/ssl/set_ssl_server_cert.vtc
index 0dbef72..3fccaa6 100644
--- a/reg-tests/ssl/set_ssl_server_cert.vtc
+++ b/reg-tests/ssl/set_ssl_server_cert.vtc
@@ -6,7 +6,7 @@
 varnishtest "Test the 'set ssl cert' feature of the CLI"
 #REQUIRE_VERSION=2.4
 #REQUIRE_OPTIONS=OPENSSL
-#REQUIRE_BINARIES=socat
+feature cmd "command -v socat"
 feature ignore_unknown_macro
 
 server s1 -repeat 4 {
diff --git a/reg-tests/ssl/show_ssl_ocspresponse.vtc b/reg-tests/ssl/show_ssl_ocspresponse.vtc
index 29673a5..387f36a 100644
--- a/reg-tests/ssl/show_ssl_ocspresponse.vtc
+++ b/reg-tests/ssl/show_ssl_ocspresponse.vtc
@@ -21,7 +21,7 @@
 varnishtest "Test the 'show ssl ocsp-response' and 'show ssl cert foo.pem.ocsp' features of the CLI"
 feature cmd "$HAPROXY_PROGRAM -cc 'version_atleast(2.5-dev0)'"
 feature cmd "$HAPROXY_PROGRAM -cc 'feature(OPENSSL)'"
-#REQUIRE_BINARIES=socat
+feature cmd "command -v socat"
 feature ignore_unknown_macro
 
 haproxy h1 -conf {