Add toolchain_clang build support

Signed-off-by: liyunfei <liyunfei33@huawei.com>

compiler-rt.spec

@@ -1,5 +1,10 @@
 %bcond_without sys_llvm
 %bcond_without check
+%bcond_without toolchain_clang
+
+%if %{with toolchain_clang}
+%global toolchain clang
+%endif
 
 %global maj_ver 17
 %global min_ver 0
@@ -27,7 +32,7 @@
 
 Name:		%{pkg_name}
 Version:	%{crt_version}
-Release:	3
+Release:	4
 Summary:	LLVM "compiler-rt" runtime libraries
 
 License:	NCSA or MIT
@@ -44,6 +49,9 @@ BuildRequires:	ninja-build
 BuildRequires:	python3
 # We need python3-devel for pathfix.py.
 BuildRequires:	python3-devel
+%if %{with toolchain_clang}
+BuildRequires:	clang
+%endif
 
 %if %{with sys_llvm}
 BuildRequires:	llvm-devel = %{version}
@@ -83,6 +91,10 @@ cd _build
 	-DLLVM_LIBDIR_SUFFIX=64 \
 %else
 	-DLLVM_LIBDIR_SUFFIX= \
+%endif
+%if "%{toolchain}" == "clang"
+	-DCMAKE_C_COMPILER=clang \
+	-DCMAKE_CXX_COMPILER=clang++ \
 %endif
 	-DCOMPILER_RT_INCLUDE_TESTS:BOOL=OFF # could be on?
 
@@ -109,6 +121,9 @@ cd _build
 %endif
 
 %changelog
+* Fri Jul 5 2024 liyunfei <liyunfei33@huawei.com> - 17.0.6-4
+- Add toolchain_clang build support
+
 * Wed Apr 03 2024 zhanglimin <zhanglimin@loongson.cn> - 17.0.6-3
 - Improve the support for compiler-rt on LoongArch