build: fix AIX xlc autotools build (libuv#3588)

configure.ac

@@ -28,7 +28,9 @@ AM_PROG_CC_C_O
 CC_ATTRIBUTE_VISIBILITY([default], [
  CC_FLAG_VISIBILITY([CFLAGS="${CFLAGS} -fvisibility=hidden"])
 ])
-CC_CHECK_CFLAGS_APPEND([-fno-strict-aliasing])
+# Xlc has a flag "-f<filename>". Need to use CC_CHECK_FLAG_SUPPORTED_APPEND so
+# we exclude -fno-strict-aliasing for xlc
+CC_CHECK_FLAG_SUPPORTED_APPEND([-fno-strict-aliasing])
 CC_CHECK_CFLAGS_APPEND([-g])
 CC_CHECK_CFLAGS_APPEND([-std=gnu89])
 CC_CHECK_CFLAGS_APPEND([-Wall])

m4/libuv-check-flags.m4

@@ -104,6 +104,20 @@ AC_DEFUN([CC_CHECK_LDFLAGS], [
  [$2], [$3])
 ])
 
+dnl Check if flag is supported by both compiler and linker
+dnl If so, append it to AM_CFLAGS
+dnl CC_CHECK_FLAG_SUPPORTED_APPEND([FLAG])
+
+AC_DEFUN([CC_CHECK_FLAG_SUPPORTED_APPEND], [
+ CC_CHECK_CFLAGS([$1],
+ [CC_CHECK_LDFLAGS([$1],
+ [AM_CFLAGS="$AM_CFLAGS $1";
+ DEBUG_CFLAGS="$DEBUG_CFLAGS $1";
+ AC_SUBST([AM_CFLAGS])
+ ])
+ ])
+])
+
 dnl define the LDFLAGS_NOUNDEFINED variable with the correct value for
 dnl the current linker to avoid undefined references in a shared object.
 AC_DEFUN([CC_NOUNDEFINED], [