check-reallocarray.sh: Use the same compiler Make does

Currently we hardcode "gcc", which means we get a bogus result any time
a non-default CC is passed to Make. In fact, it's bogus even when CC is
not explicitly set, since Make's default is "cc", which isn't
necessarily the same as "gcc".

Fix the issue by passing the compiler to use to check-reallocarray.sh.

Signed-off-by: Thomas Hebb <tommyhebb@gmail.com>

scripts/check-reallocarray.sh

@@ -1,4 +1,5 @@
 #!/bin/sh
+# Usage: check-reallocarray.sh cc_path [cc_args...]
 
 tfile=$(mktemp /tmp/test_reallocarray_XXXXXXXX.c)
 ofile=${tfile%.c}.o
@@ -13,6 +14,6 @@ int main(void)
 }
 EOL
 
-gcc $tfile -o $ofile >/dev/null 2>&1
+"$@" $tfile -o $ofile >/dev/null 2>&1
 if [ $? -ne 0 ]; then echo "FAIL"; fi
 /bin/rm -f $tfile $ofile

src/Makefile

@@ -10,7 +10,7 @@ TOPDIR = ..
 INCLUDES := -I. -I$(TOPDIR)/include -I$(TOPDIR)/include/uapi
 ALL_CFLAGS := $(INCLUDES)
 
-FEATURE_REALLOCARRAY := $(shell $(TOPDIR)/scripts/check-reallocarray.sh)
+FEATURE_REALLOCARRAY := $(shell $(TOPDIR)/scripts/check-reallocarray.sh $(CC))
 ifneq ($(FEATURE_REALLOCARRAY),)
 	ALL_CFLAGS += -DCOMPAT_NEED_REALLOCARRAY
 endif