Revert "Add extendhfxf2 into compiler rt (llvm#111099)"

This reverts commit 5f7bad0.

These tests fail to build in multiple configurations, see
llvm#111099.

Author: mstorsjo

compiler-rt/lib/builtins/CMakeLists.txt

@@ -104,7 +104,6 @@ set(GENERIC_SOURCES
   divti3.c
   extendsfdf2.c
   extendhfsf2.c
-  extendhfxf2.c
   ffsdi2.c
   ffssi2.c
   ffsti2.c

compiler-rt/lib/builtins/extendhfxf2.c

@@ -60,7 +60,6 @@ divsf3
 divsi3
 extendsfdf2
 extendhfsf2
-extendhfxf2
 ffssi2
 fixdfsi
 fixsfsi

compiler-rt/lib/builtins/macho_embedded/common.txt

@@ -126,7 +126,6 @@ static_library("builtins") {
     "divsi3.c",
     "divti3.c",
     "extendhfsf2.c",
-    "extendhfxf2.c"
     "extendsfdf2.c",
     "ffsdi2.c",
     "ffssi2.c",