package/webkitgtk: also disable internal ccache in the build step

WK_USE_CCACHE=NO is only passed to the configure step
(WEBKITGTK_CONF_ENV). During the build step, ninja can run cmake again
(e.g. when a cmake input such as toolchainfile.cmake changed), and that
run does not have WK_USE_CCACHE set. WebKit's WebKitCCache.cmake then
sets ccache as compiler launcher again.

That outer ccache runs without the CCACHE_BASEDIR that the toolchain
wrapper sets for its own ccache call, so the cache keys and manifests
contain absolute paths, and the entries only match in the same checkout
directory.

Pass WK_USE_CCACHE=NO to the build step too.

Signed-off-by: Thomas Devoogdt <thomas.devoogdt@barco.com>
Acked-by: Adrian Perez de Castro <aperez@igalia.com>
Signed-off-by: Arnout Vandecappelle <arnout@rnout.be>
(cherry picked from commit 9f0aacb634)
Signed-off-by: Raphaël Mélotte <raphael.melotte@mind.be>

package/webkitgtk/webkitgtk.mk

@@ -22,6 +22,7 @@ WEBKITGTK_CMAKE_BACKEND = ninja
 # Buildroot adds support for ccache through its
 # toolchain-wrapper, so tell webkitgtk not to mess with it.
 WEBKITGTK_CONF_ENV = WK_USE_CCACHE=NO
+WEBKITGTK_BUILD_ENV = WK_USE_CCACHE=NO
 
 WEBKITGTK_CONF_OPTS = \
 	-DENABLE_API_TESTS=OFF \