sdl: fix build of other sdl components

The post installation hook of SDL was not being executed, due to an
incorrect usage of the infrastructure. Moreover, it did not patch
prefix/exec_prefix in sdl-config as is needed. In addition to that, we
remove the -Wl,-rpath option from sdl-config, since it is not needed.

This fixes at least the build of sdl_image, and probably of other sdl
components as well.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/sdl/sdl.mk

@@ -46,11 +46,19 @@ SDL_CONF_OPT += --enable-pulseaudio=no \
 		--disable-esd \
 		--disable-nasm
 
-define SDL_POST_INSTALL_STAGING_HOOKS
-       $(SED) 's^libdir=\$${exec_prefix}^libdir=/usr^' \
-               $(STAGING_DIR)/usr/bin/sdl-config
+# Fixup prefix= and exec_prefix= in sdl-config, and remove the
+# -Wl,-rpath option.
+define SDL_FIXUP_SDL_CONFIG
+	$(SED) 's%prefix=/usr%prefix=$(STAGING_DIR)/usr%' \
+		$(STAGING_DIR)/usr/bin/sdl-config
+	$(SED) 's%exec_prefix=/usr%exec_prefix=$(STAGING_DIR)/usr%' \
+		$(STAGING_DIR)/usr/bin/sdl-config
+	$(SED) 's%-Wl,-rpath,\$${libdir}%%' \
+		$(STAGING_DIR)/usr/bin/sdl-config
 endef
 
+SDL_POST_INSTALL_STAGING_HOOKS+=SDL_FIXUP_SDL_CONFIG
+
 define SDL_INSTALL_TARGET_CMDS
 	cp -dpf $(STAGING_DIR)/usr/lib/libSDL*.so* $(TARGET_DIR)/usr/lib/
 endef