Support Clang for building

(cherry picked from commit b6a4fc70dfa45551bbd20b93e13a6a3b84b40367)

p7zip.spec

@@ -1,6 +1,6 @@
 Name:    p7zip
 Version: 16.02
-Release: 6
+Release: 7
 Summary: 7z for Linux system
 License: LGPLv2 and (LGPLv2+ or CPL)
 URL:	 https://sourceforge.net/projects/p7zip/
@@ -20,6 +20,11 @@ BuildRequires: 	gcc-c++
 %prep
 %autosetup -n %{name}_%{version} -p1
 
+%if "%toolchain" == "clang"
+  sed -i 's/^CC=gcc/CC=clang/' makefile.*
+  sed -i 's/^CXX=g++/CXX=clang++/' makefile.*
+%endif
+
 %build
 %make_build OPTFLAGS="%{build_cxxflags}" LDFLAGS="%{build_ldflags}"
 
@@ -42,6 +47,9 @@ install -m 0644 man1/7za.1 %{buildroot}/%{_mandir}/man1
 %{_mandir}/*
 
 %changelog
+* Tue Jan 07 2025 Suyun <ziyu.oerv@isrc.iscas.ac.cn> - 16.02-7
+- Support Clang for building
+
 * Sat Aug 31 2024 Funda Wang <fundawang@yeah.net> - 16.02-6
 - use correct build flags