libsdl-ttf: Fix build with separate builddir

Do not assume that sources are in the current directory in
do_configure_prepend() but refer to them with path to source directory.

Signed-off-by: Marko Lindqvist <cazfi74@gmail.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

meta-oe/recipes-support/libsdl-ttf/libsdl-ttf_2.0.10.bb

@@ -4,7 +4,7 @@ DEPENDS = "virtual/libsdl freetype"
 LICENSE = "LGPLv2.1"
 LIC_FILES_CHKSUM = "file://COPYING;md5=27818cd7fd83877a8e3ef82b82798ef4"
 
-PR = "r1"
+PR = "r2"
 
 SRC_URI = "http://www.libsdl.org/projects/SDL_ttf/release/SDL_ttf-${PV}.tar.gz \
            file://configure.patch \
@@ -18,11 +18,12 @@ inherit autotools
 TARGET_CC_ARCH += "${LDFLAGS}"
 
 do_configure_prepend() {
-  
+
+    # Removing these files fixes a libtool version mismatch.
     MACROS="libtool.m4 lt~obsolete.m4 ltoptions.m4 ltsugar.m4 ltversion.m4"
- 
+
     for i in ${MACROS}; do
-     rm acinclude/$i
+      rm ${S}/acinclude/$i
     done
 
 }