MINOR: show PCRE version and JIT status in -vv

haproxy -vv shows build informations about USE flags and lib versions.
This patch introduces informations about PCRE and the new JIT feature.
It also makes USE_PCRE_JIT=1 appear in the haproxy -vv "OPTIONS".

This is useful since with the introduction of JIT we will see libpcre
related issues.
diff --git a/Makefile b/Makefile
index f2ac373..68e2ff8 100644
--- a/Makefile
+++ b/Makefile
@@ -562,6 +562,7 @@
 # JIT PCRE
 ifneq ($(USE_PCRE_JIT),)
 OPTIONS_CFLAGS  += -DUSE_PCRE_JIT
+BUILD_OPTIONS   += $(call ignore_implicit,USE_PCRE_JIT)
 endif
 endif