Add a test checking that each SIMD intrinsic produces the expected instruction.
Since this test spans both clang and LLVM, place it in a new
intrinsic-header-tests subdirectory of cross-project-tests.
This revives D101684 now that cross-project-tests exists. In practice, the tests
of lowering from wasm_simd128.h to LLVM IR were not as useful as this end-to-end
test.
Updates the version check of gdb in cross-project-tests/lit.cfg.py so that
unexpected version formats do not prevent the new tests from running.
Depends on D121661.
Differential Revision: https://reviews.llvm.org/D121662
Thomas Lively