!42 Add toolchain_clang build support

From: @liyunfei33 
Reviewed-by: @cf-zhao 
Signed-off-by: @cf-zhao

llvm-bolt.spec

@@ -1,5 +1,10 @@
 %bcond_without sys_llvm
 %bcond_with check
+%bcond_without toolchain_clang
+
+%if %{with toolchain_clang}
+%global toolchain clang
+%endif
 
 %global maj_ver 17
 %global min_ver 0
@@ -22,7 +27,7 @@
 
 Name:           %{pkg_name}
 Version:        %{bolt_version}
-Release:        1
+Release:        2
 Summary:        BOLT is a post-link optimizer developed to speed up large applications
 License:        Apache 2.0
 URL:            https://github.com/llvm/llvm-project/tree/main/bolt
@@ -43,6 +48,9 @@ BuildRequires:  zlib-devel
 BuildRequires:  python3-lit
 BuildRequires:  python3-psutil
 BuildRequires:  doxygen
+%if %{with toolchain_clang}
+BuildRequires:	clang
+%endif
 
 %description
 BOLT is a post-link optimizer developed to speed up large applications.
@@ -77,6 +85,10 @@ Documentation for the BOLT optimizer
          -DLLVM_EXTERNAL_LIT=%{_bindir}/lit \
          -DLLVM_ENABLE_PROJECTS="bolt" \
          -DLLVM_PARALLEL_LINK_JOBS=%{max_link_jobs} \
+%if "%{toolchain}" == "clang"
+         -DCMAKE_C_COMPILER=clang \
+         -DCMAKE_CXX_COMPILER=clang++ \
+%endif
 %ifarch %ix86 x86_64
          -DLLVM_TARGETS_TO_BUILD="X86"
 %endif
@@ -148,6 +160,9 @@ rm -f %{buildroot}/%{_builddir}/%{bolt_srcdir}/%{_vpath_builddir}/%{_lib}/lib*.a
 
 
 %changelog
+* Fri Jul 5 2024 liyunfei <liyunfei33@huawei.com> - 17.0.6-2
+- Add toolchain_clang build support
+
 * Mon Dec 4 2023 zhoujing <zhoujing106@huawei.com> 17.0.6-1
 - Update to 17.0.6