Revert "[compiler-rt] [builtins] Detect _Float16 support at compile time"

This reverts commit ce6d40f5c23923a807388c58b82b4c343eced0ce.

Revert due to it broke the sanitizer-windows buildbot: https://lab.llvm.org/buildbot/#/builders/127/builds/33583/steps/4/logs/stdio

GitOrigin-RevId: b17c89d1511f14b864ee680577a7b68363d672f9
11 files changed