[libclc] Allow default path when looking for llvm-spirv (llvm#126071)

This is an external tool, so I don't think there is an expectation that
it has to be in the LLVM tools bindir. It may also be in the default
system bindir (which is not necessarily the same).

(cherry picked from commit 26ecddb)

Author: nikic

libclc/CMakeLists.txt

@@ -114,7 +114,7 @@ endforeach()
 if( TARGET llvm-spirv )
   get_host_tool_path( llvm-spirv LLVM_SPIRV llvm-spirv_exe llvm-spirv_target )
 else()
-  find_program( LLVM_SPIRV llvm-spirv PATHS ${LLVM_TOOLS_BINARY_DIR} NO_DEFAULT_PATH )
+  find_program( LLVM_SPIRV llvm-spirv HINTS ${LLVM_TOOLS_BINARY_DIR} )
   set( llvm-spirv_exe "${LLVM_SPIRV}" )
   set( llvm-spirv_target )
 endif()