cmake: Install libraries to DATADIR from GNUInstallDirs

This moves default installation location to /usr/share to match libclc.pc.
Signed-off-by: Jan Vesely <jan.vesely@rutgers.edu>
Reviewer: Tom Stellard

llvm-svn: 350565
GitOrigin-RevId: e25db17104bc4d1cbc9f4aa0d073d33c74b34848
2 files changed