Revert: check-builtins target for LLVM_ENABLE_RUNTIMES

[ndrewh]

Revert #171741 and #166837.

@petrhosek reported issues with some builders using this feature

[llvm-ci]

LLVM Buildbot has detected a new failure on builder clang-ppc64le-linux-test-suite running on ppc64le-clang-test-suite while building compiler-rt,llvm at step 6 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/95/builds/19414

Here is the relevant piece of the build log for the reference

Step 6 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'Clangd :: crash-parse.test' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 1
not --crash clangd -lit-test < /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/llvm-project/clang-tools-extra/clangd/test/crash-parse.test 2> /home/buildbots/llvm-external-buildbots/workers/ppc64le-clang-test-suite/clang-ppc64le-test-suite/build/tools/clang/tools/extra/clangd/test/Output/crash-parse.test.tmp.err
# executed command: not --crash clangd -lit-test
# .---command stdout------------
# | Content-Length: 3441
# | 
# | {
# |   "id": 0,
# |   "jsonrpc": "2.0",
# |   "result": {
# |     "capabilities": {
# |       "astProvider": true,
# |       "callHierarchyProvider": true,
# |       "clangdInlayHintsProvider": true,
# |       "codeActionProvider": true,
# |       "compilationDatabase": {
# |         "automaticReload": true
# |       },
# |       "completionProvider": {
# |         "resolveProvider": false,
# |         "triggerCharacters": [
# |           ".",
# |           "<",
# |           ">",
# |           ":",
# |           "\"",
# |           "/",
# |           "*"
# |         ]
# |       },
# |       "declarationProvider": true,
# |       "definitionProvider": true,
# |       "documentFormattingProvider": true,
# |       "documentHighlightProvider": true,
# |       "documentLinkProvider": {
# |         "resolveProvider": false
# |       },
# |       "documentOnTypeFormattingProvider": {
# |         "firstTriggerCharacter": "\n",
# |         "moreTriggerCharacter": []
# |       },
# |       "documentRangeFormattingProvider": {
# |         "rangesSupport": true
# |       },
# |       "documentSymbolProvider": true,
...