Revert "Revert "Revert "[compiler-rt] Allow building builtins.a without a libc (#86737)"""

This reverts commit d2b63ed0ca5c7eb3f8fc029e3a5705cf0ddab438. CI again.
Leading theory is bad interaction between cmake and buildbot, some guesses at PR86737

GitOrigin-RevId: ca68a14eb822d88bc32d511258f261e88dd6b7d6
1 file changed