autoconf: correctly parse *_INCLUDES and *_LIB env vars

Parse those options correctly, since the "+=" operator is not valid.
Also added CPPFLAGS, so headers checks don't give strange results.

Please rerun configure after applying.

Signed-off-by: Roger Pau Monne <roger.pau@citrix.com>
Cc: Christoph Egger <Christoph.Egger@amd.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>

tools/configure

@@ -2594,23 +2594,23 @@ debug=$ax_cv_debug
 
 
 
-for cflag in $PREPEND_INCLUDES
+for cppflag in $PREPEND_INCLUDES
 do
-    PREPEND_CFLAGS+=" -I$cflag"
+    PREPEND_CPPFLAGS="$PREPEND_CPPFLAGS -I$cppflag"
 done
 for ldflag in $PREPEND_LIB
 do
-    PREPEND_LDFLAGS+=" -L$ldflag"
+    PREPEND_LDFLAGS="$PREPEND_LDFLAGS -L$ldflag"
 done
-for cflag in $APPEND_INCLUDES
+for cppflag in $APPEND_INCLUDES
 do
-    APPEND_CFLAGS+=" -I$cflag"
+    APPEND_CPPFLAGS="$APPEND_CPPFLAGS -I$cppflag"
 done
 for ldflag in $APPEND_LIB
 do
-    APPEND_LDFLAGS+=" -L$ldflag"
+    APPEND_LDFLAGS="$APPEND_LDFLAGS -L$ldflag"
 done
-CFLAGS="$PREPEND_CFLAGS $CFLAGS $APPEND_CFLAGS"
+CPPFLAGS="$PREPEND_CPPFLAGS $CPPFLAGS $APPEND_CPPFLAGS"
 LDFLAGS="$PREPEND_LDFLAGS $LDFLAGS $APPEND_LDFLAGS"
 
 

tools/m4/set_cflags_ldflags.m4

@@ -1,20 +1,20 @@
 AC_DEFUN([AX_SET_FLAGS],
-[for cflag in $PREPEND_INCLUDES
+[for cppflag in $PREPEND_INCLUDES
 do
-    PREPEND_CFLAGS+=" -I$cflag"
+    PREPEND_CPPFLAGS="$PREPEND_CPPFLAGS -I$cppflag"
 done
 for ldflag in $PREPEND_LIB
 do
-    PREPEND_LDFLAGS+=" -L$ldflag"
+    PREPEND_LDFLAGS="$PREPEND_LDFLAGS -L$ldflag"
 done
-for cflag in $APPEND_INCLUDES
+for cppflag in $APPEND_INCLUDES
 do
-    APPEND_CFLAGS+=" -I$cflag"
+    APPEND_CPPFLAGS="$APPEND_CPPFLAGS -I$cppflag"
 done
 for ldflag in $APPEND_LIB
 do
-    APPEND_LDFLAGS+=" -L$ldflag"
+    APPEND_LDFLAGS="$APPEND_LDFLAGS -L$ldflag"
 done
-CFLAGS="$PREPEND_CFLAGS $CFLAGS $APPEND_CFLAGS"
+CPPFLAGS="$PREPEND_CPPFLAGS $CPPFLAGS $APPEND_CPPFLAGS"
 LDFLAGS="$PREPEND_LDFLAGS $LDFLAGS $APPEND_LDFLAGS"])