Revert "clang: Use new frexp intrinsic for builtins and add f16 version"

This caused asserts in some Android and Windows builds:

SelectionDAGNodes.h:1138: llvm::SDValue::SDValue(SDNode *, unsigned int):
Assertion `(!Node || !ResNo || ResNo < Node->getNumValues()) && "Invalid result number for the given node!"' failed.

See comment on https://github.com/llvm/llvm-project/commit/85bdea023f5116f789095b606554739403042a21

Also revert "HIP: Use frexp builtins in math headers"
which seems to depend on this change.

This reverts commit 85bdea02.
This reverts commit bf8e92c0.