BUILD: makefile: fix regex syntax in ARM platform detection
Commit d93e6ec ("BUILD: on ARM, must be linked to libatomic.") broke the
build due to a missing backslash in front of the '#':
Makefile:331: *** invalid syntax in conditional. Stop.
Let's address this and make sure we only pick relevant lines (and not
possibly empty lines).
diff --git a/Makefile b/Makefile
index 469001a..959d5b7 100644
--- a/Makefile
+++ b/Makefile
@@ -328,7 +328,7 @@
USE_CPU_AFFINITY USE_THREAD USE_EPOLL USE_FUTEX USE_LINUX_TPROXY \
USE_ACCEPT4 USE_LINUX_SPLICE USE_PRCTL USE_THREAD_DUMP USE_NS USE_TFO \
USE_GETADDRINFO USE_BACKTRACE)
-ifneq ($(shell echo __arm__/__aarch64__ | $(CC) -E -xc - | grep -v '^#'),__arm__/__aarch64__)
+ifneq ($(shell echo __arm__/__aarch64__ | $(CC) -E -xc - | grep -v '^[^\#]'),__arm__/__aarch64__)
TARGET_LDFLAGS=-latomic
endif
endif