pkgconf: fix incorrect variable-directory sysroot prefixing

According to the pkg-config documents ("specification") when
sysroot-prefixing is enabled via PKG_CONFIG_SYSROOT_DIR this should only
be applied to -I/-L directories (includes, library directories), and not
to all of the other variables that can specify a directory.

However xorg uses mapdir/sdkdir in a similar fashion in what could be
considered an abuse of the spec, hence needs to be prefixed as well.
And what's more, it also uses includedir in a nonstandard fashion just
requesting the value via 'pkg-config --variable=includedir libfoo' which
doesn't pass the standard prefixing rules for the --cflags and --libs
invocation.

This patch makes pkgconf behave in the pkg-config specified way with the
added exception for the includedir, libdir, mapdir and sdkdir variables
which are prefixed.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Tested-by: Peter Seiderer <ps.report@gmx.net>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/pkgconf/0001-Fix-all-variables-sysroot-prefix-problem.patch

@@ -0,0 +1,58 @@
+From abc7a780f2a52a1aa3ee288e17140b817b545cc3 Mon Sep 17 00:00:00 2001
+From: Gustavo Zacarias <gustavo@zacarias.com.ar>
+Date: Mon, 2 Nov 2015 18:38:00 -0300
+Subject: [PATCH] Fix all-variables sysroot prefix problem
+
+According to the pkg-config specifications (or rather documentation)
+only the -L/-I directory entries should be sysroot-prefixed.
+
+We also need to prefix the mapdir/sdkdir variables since they're used by
+xorg and expected that way.
+
+Also allow prefixing for includedir and libdir since in some silly cases
+the directories may be requested barebones via pkg-config
+--variable=includedir libfool for example.
+
+Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
+---
+ main.c | 17 ++++++++++++-----
+ 1 file changed, 12 insertions(+), 5 deletions(-)
+
+diff --git a/main.c b/main.c
+index 6947126..52d16c2 100644
+--- a/main.c
++++ b/main.c
+@@ -313,9 +313,12 @@ print_variable(pkg_t *pkg, void *data, unsigned int flags)
+ 			memset(req->buf, 0, sizeof(req->buf));
+ 
+ 			if (*var == '/' && (flags & PKGF_MUNGE_SYSROOT_PREFIX) &&
+-			    (sysroot_dir != NULL && strncmp(var, sysroot_dir, strlen(sysroot_dir))))
+-				strlcat(req->buf, sysroot_dir, sizeof(req->buf));
+-
++			    (sysroot_dir != NULL && strncmp(var, sysroot_dir, strlen(sysroot_dir))) &&
++			    	(!strcmp(req->variable, "includedir") || \
++				    !strcmp(req->variable, "libdir") || \
++				    !strcmp(req->variable, "mapdir") || \
++				    !strcmp(req->variable, "sdkdir")))
++					strlcat(req->buf, sysroot_dir, sizeof(req->buf));
+ 			strlcat(req->buf, var, sizeof(req->buf));
+ 			return;
+ 		}
+@@ -323,8 +326,12 @@ print_variable(pkg_t *pkg, void *data, unsigned int flags)
+ 		strlcat(req->buf, " ", sizeof(req->buf));
+ 
+ 		if (*var == '/' && (flags & PKGF_MUNGE_SYSROOT_PREFIX) &&
+-		    (sysroot_dir != NULL && strncmp(var, sysroot_dir, strlen(sysroot_dir))))
+-			strlcat(req->buf, sysroot_dir, sizeof(req->buf));
++		    (sysroot_dir != NULL && strncmp(var, sysroot_dir, strlen(sysroot_dir))) &&
++		    	(!strcmp(req->variable, "includedir") || \
++			    !strcmp(req->variable, "libdir") || \
++			    !strcmp(req->variable, "mapdir") || \
++			    !strcmp(req->variable, "sdkdir")))
++				strlcat(req->buf, sysroot_dir, sizeof(req->buf));
+ 
+ 		strlcat(req->buf, var, sizeof(req->buf));
+ 	}
+-- 
+2.4.10
+