must give hint to libtool which tag to use, in case we use ccache and then
libtool is unable to autodetect from $CC
---- apr-1.3.0/configure.in.orig 2008-06-16 22:57:25.596627316 +0200
-+++ apr-1.3.0/configure.in 2008-06-16 22:58:16.295519834 +0200
-@@ -197,9 +197,9 @@
+--- apr-1.5.0/configure.in.orig 2013-11-22 17:29:57.303051538 +0100
++++ apr-1.5.0/configure.in 2013-11-22 17:31:11.273048433 +0100
+@@ -280,9 +280,9 @@
[ use_libtool=$withval ], [ use_libtool="yes" ] )
if test "x$use_libtool" = "xyes"; then
- lt_compile='$(LIBTOOL) $(LTFLAGS) --mode=compile $(COMPILE) -o $@ -c $< && touch $@'
+ lt_compile='$(LIBTOOL) $(LTFLAGS) --mode=compile --tag=CC $(COMPILE) -o $@ -c $< && touch $@'
LT_VERSION="-version-info `$get_version libtool $version_hdr APR`"
-- link="\$(LIBTOOL) \$(LTFLAGS) --mode=link \$(LT_LDFLAGS) \$(COMPILE) \$(LT_VERSION) \$(ALL_LDFLAGS) -o \$@"
-+ link="\$(LIBTOOL) \$(LTFLAGS) --mode=link --tag=CC \$(LT_LDFLAGS) \$(COMPILE) \$(LT_VERSION) \$(ALL_LDFLAGS) -o \$@"
+- link="\$(LIBTOOL) \$(LTFLAGS) --mode=link \$(COMPILE) \$(LT_LDFLAGS) \$(LT_VERSION) \$(ALL_LDFLAGS) -o \$@"
++ link="\$(LIBTOOL) \$(LTFLAGS) --mode=link --tag=CC \$(COMPILE) \$(LT_LDFLAGS) \$(LT_VERSION) \$(ALL_LDFLAGS) -o \$@"
so_ext='lo'
lib_target='-rpath $(libdir) $(OBJECTS)'
export_lib_target='-rpath \$(libdir) \$(OBJECTS)'