armv7l is referred to as armhf in LLVM. While compiler-rt/CMakeLists.txt
already performs this replacement, it does not seem to be applied in all
places where it is needed.

In compiler-rt/lib/builtins/CMakeLists.txt, the incorrect value is used,
which prevents creation of the clang_rt.builtins-${arch}.sources.txt file
for the target architecture, because armv7l is not included in the
BUILTIN_SUPPORTED_ARCH list.

As a result, compiler-rt/test/builtins/CMakeLists.txt is unable to read the
clang_rt.builtins-armhf.sources.txt file.

CMake Error at /builddir/llvm22-22.1.1/compiler-rt/test/builtins/CMakeLists.txt:110 (file):
  file failed to open for reading (No such file or directory):
    /builddir/llvm22-22.1.1/llvm/build/./lib/../lib/clang/22/lib/linux/clang_rt.builtins-armhf.sources.txt

--- a/compiler-rt/cmake/Modules/CompilerRTUtils.cmake
+++ b/compiler-rt/cmake/Modules/CompilerRTUtils.cmake
@@ -413,6 +413,10 @@
     set(COMPILER_RT_DEFAULT_TARGET_ARCH "i386")
   endif()
 
+  if("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "^armv7l$")
+    set(COMPILER_RT_DEFAULT_TARGET_ARCH "armhf")
+  endif()
+
   # If we are directly targeting a GPU we need to check that the compiler is
   # compatible and pass some default arguments.
   if(COMPILER_RT_DEFAULT_TARGET_ONLY)
