libhsakmt: Fix pkg-config file paths

Both the include and libpath were incorrect after recent build
system changes. Use the proper GNUInstallDirs definitions in
libhsakmt.pc.in to write the proper locations.

This is needed for end users building KFDTest, which depends on
correct pkg-config information.

Change-Id: Ia45f36f054c2a607a77e7ecbcbd9eb7edd067348
Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>

libhsakmt.pc.in

@@ -1,7 +1,7 @@
 prefix=@CPACK_PACKAGING_INSTALL_PREFIX@
 exec_prefix=${prefix}
-libdir=${prefix}/lib
-includedir=${prefix}/include/libhsakmt
+libdir=${prefix}/@CMAKE_INSTALL_LIBDIR@
+includedir=${prefix}/@CMAKE_INSTALL_INCLUDEDIR@
 
 Name: libhsakmt
 Description: HSA Kernel Mode Thunk library for AMD KFD support