build-sys: Fix warning in use-case.h configure check

AC_CHECK_HEADER uses cpp for header checks, so in order for the check to use
the right flags, we need to override CPPFLAGS and not CFLAGS.

diff --git a/configure.ac b/configure.ac
index 438fd06fc6590fba39cd66240a43553ee1544cd9..15f2f9975bb4929a3bba4d1797443aa7e86c7ae5 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -770,9 +770,9 @@ AS_IF([test "x$enable_alsa" = "xyes" && test "x$HAVE_ALSA" = "x0"],
 
 AS_IF([test "x$HAVE_ALSA" = "x1"],
     [
-        save_CFLAGS="$CFLAGS"; CFLAGS="$CFLAGS $ASOUNDLIB_CFLAGS"
+        save_CPPFLAGS="$CPPFLAGS"; CPPFLAGS="$CPPFLAGS $ASOUNDLIB_CFLAGS"
         AC_CHECK_HEADERS([use-case.h], HAVE_ALSA_UCM=1, HAVE_ALSA_UCM=0)
-        CFLAGS="$save_CFLAGS"
+        CPPFLAGS="$save_CPPFLAGS"
     ],
     HAVE_ALSA_UCM=0)