devel/libclc: Update llvm19 flavor and add 20, 21, and 22 flavors

Rename plist variables LLVMnn to LLVM_GEnn (>=nn) and introduce
LLVM_LTnn (<nn).

Convert patch to REINPLACE_CMD because it fails to apply to the
LLVM 22 version.

PR: 290873
Approved by: arrowd