libselinux, libsepol: Add CFLAGS and LDFLAGS to Makefile checks

In libselinux there is an availability check for strlcpy() and
in both libselinux and libsepol there are availability checks for
reallocarray() in the src Makfiles. CFLAGS and LDFLAGS are needed
for cross-compiling, but, unfortunately, the default CFLAGS cause
all of these availability checks to fail to compile because of
compilationerrors (rather than just the function not being available).

Add CFLAGS and LDFLAGS to the availibility checks, update the checks
so that a compilation error will only happen if the function being
checked for is not available, and make checks for the same function
the same in both libselinux and libsepol.

Suggested-by: Jordan Williams <[email protected]>
Suggested-by: Winfried Dobbe <[email protected]>
Signed-off-by: James Carter <[email protected]>

libselinux/src/Makefile

@@ -104,13 +104,13 @@ override CFLAGS += -I../include -D_GNU_SOURCE $(DISABLE_FLAGS) $(PCRE_CFLAGS)
 
 # check for strlcpy(3) availability
 H := \#
-ifeq (yes,$(shell printf '${H}include <string.h>\nint main(void){char*d,*s;strlcpy(d, s, 0);return 0;}' | $(CC) -x c -o /dev/null - >/dev/null 2>&1 && echo yes))
+ifeq (yes,$(shell printf '${H}include <string.h>\nint main(void){char d[2];const char *s="a";return (size_t)strlcpy(d,s,sizeof(d))>=sizeof(d);}' | $(CC) $(CFLAGS) $(LDFLAGS) -x c -o /dev/null - >/dev/null 2>&1 && echo yes))
 override CFLAGS += -DHAVE_STRLCPY
 endif
 
 # check for reallocarray(3) availability
 H := \#
-ifeq (yes,$(shell printf '${H}include <stdlib.h>\nint main(void){reallocarray(NULL, 0, 0);return 0;}' | $(CC) -x c -o /dev/null - >/dev/null 2>&1 && echo yes))
+ifeq (yes,$(shell printf '${H}include <stdlib.h>\nint main(void){return reallocarray(NULL,0,0)==NULL;}' | $(CC) $(CFLAGS) $(LDFLAGS) -x c -o /dev/null - >/dev/null 2>&1 && echo yes))
 override CFLAGS += -DHAVE_REALLOCARRAY
 endif
 

libsepol/src/Makefile

@@ -31,7 +31,7 @@ endif
 
 # check for reallocarray(3) availability
 H := \#
-ifeq (yes,$(shell printf '${H}define _GNU_SOURCE\n${H}include <stdlib.h>\nint main(void){void*p=reallocarray(NULL, 1, sizeof(char));return 0;}' | $(CC) $(LDFLAGS) -x c -o /dev/null - >/dev/null 2>&1 && echo yes))
+ifeq (yes,$(shell printf '${H}include <stdlib.h>\nint main(void){return reallocarray(NULL,0,0)==NULL;}' | $(CC) $(CFLAGS) $(LDFLAGS) -x c -o /dev/null - >/dev/null 2>&1 && echo yes))
 override CFLAGS += -DHAVE_REALLOCARRAY
 endif