trylink: respect compiler settings when probing features

The CPPFLAGS/CFLAGS settings might have features that matter, so make
sure we utilize them when testing the compiler.

URL: https://bugs.gentoo.org/471118
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/scripts/trylink b/scripts/trylink
index 5a67fcf..48c487b 100755
--- a/scripts/trylink
+++ b/scripts/trylink
@@ -49,7 +49,7 @@
     local tempname="$(mktemp)"
     # Can use "-o /dev/null", but older gcc tend to *unlink it* on failure! :(
     # "-xc": C language. "/dev/null" is an empty source file.
-    if $CC $1 -shared -xc /dev/null -o "$tempname".o >/dev/null 2>&1; then
+    if $CC $CPPFLAGS $CFLAGS $1 -shared -xc /dev/null -o "$tempname".o >/dev/null 2>&1; then
 	echo "$1";
     else
 	echo "$2";
@@ -66,7 +66,7 @@
 	syntax error here
 	#endif
 	" >"$tempname".c
-    if $CC "$tempname".c -c -o "$tempname".o >/dev/null 2>&1; then
+    if $CC $CPPFLAGS $CFLAGS "$tempname".c -c -o "$tempname".o >/dev/null 2>&1; then
 	echo "$2";
     else
 	echo "$1";