Revert "build: llvm libs may not be in system search path, add rpath"

Revert "build: llvm libs may not be in system search path, add rpath"

This reverts commit d9b983519c63b9072677364a6e399d213a1855e5.

Unfortunately it seems like rpath is evaluated before LD_LIBRARY_PATH,
so this breaks e.g. steam, as well as any other user of that env var,
if the llvm path happens to be where other libs also reside.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=76082
Reviewed-by: Tom Stellard <thomas.stellard@amd.com>
Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>