clover/meson: Ignore 'svn' suffix when computing CLANG_RESOURCE_DIR

clover/meson: Ignore 'svn' suffix when computing CLANG_RESOURCE_DIR

The version exported by LLVM in its CMake configuration files can
include the “svn” suffix when building a development version (for
example “8.0.0svn”). However the exported clang headers are still found
under “lib/clang/8.0.0/”, without the “svn” suffix.
Meson takes care of removing the “svn” suffix from the version when
using the dependency’s `version()` method.

This processing is already performed in “configure.ac” when using
autotools.

Signed-off-by: Pierre Moreau <pierre.morrow@free.fr>
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>