Clean up macros that allow building with clang

This adds the --with toolchain_clang option which can be passed to
fedpkg, mock, or rpmbuild to allow for building with clang.  It also
changes the conditional parts of the spec that are only used for
building with clang to check the value of the generic %toolchain macro
rather than a macro that is specific to thunderbird.

thunderbird.spec

@@ -19,7 +19,7 @@ ExcludeArch: armv7hl
 %define system_ffi    1
 
 %define build_langpacks 1
-%global build_with_clang  0
+%bcond_with toolchain_clang
 %global use_bundled_cbindgen  1
 
 %global disable_elfhack       1
@@ -89,6 +89,10 @@ ExcludeArch: s390x
 %endif
 %endif
 
+%if %{with toolchain_clang}
+%global toolchain clang
+%endif
+
 # Exclude private libraries from autogenerated provides and requires
 %global __provides_exclude_from ^%{mozappdir}
 %global __requires_exclude ^(%%(find %{buildroot}%{mozappdir} -name '*.so' | xargs -n1 basename | sort -u | paste -s -d '|' -))
@@ -96,7 +100,7 @@ ExcludeArch: s390x
 Summary:        Mozilla Thunderbird mail/newsgroup client
 Name:           thunderbird
 Version:        91.11.0
-Release:        1%{?dist}
+Release:        2%{?dist}
 URL:            http://www.mozilla.org/projects/thunderbird/
 License:        MPLv1.1 or GPLv2+ or LGPLv2+
 Source0:        https://archive.mozilla.org/pub/thunderbird/releases/%{version}%{?pre_version}/source/thunderbird-%{version}%{?pre_version}.source.tar.xz
@@ -178,7 +182,7 @@ BuildRequires:  llvm
 BuildRequires:  llvm-devel
 BuildRequires:  clang
 BuildRequires:  clang-libs
-%if 0%{?build_with_clang}
+%if "%toolchain" == "clang"
 BuildRequires:  lld
 %endif
 %if %{?system_ffi}
@@ -494,7 +498,7 @@ MOZ_OPT_FLAGS=$(echo "$MOZ_OPT_FLAGS" | %{__sed} -e 's/-g/-g0/')
 export MOZ_DEBUG_FLAGS=" "
 %endif
 
-%if !0%{?build_with_clang}
+%if "%toolchain" != "clang"
 %ifarch s390 ppc aarch64 %{ix86}
 MOZ_LINK_FLAGS="-Wl,--no-keep-memory -Wl,--reduce-memory-overheads"
 %endif
@@ -518,7 +522,7 @@ echo "export CFLAGS=\"$MOZ_OPT_FLAGS\"" >> .mozconfig
 echo "export CXXFLAGS=\"$MOZ_OPT_FLAGS\"" >> .mozconfig
 echo "export LDFLAGS=\"$MOZ_LINK_FLAGS\"" >> .mozconfig
 
-%if 0%{?build_with_clang}
+%if "%toolchain" == "clang"
 echo "export LLVM_PROFDATA=\"llvm-profdata\"" >> .mozconfig
 echo "export AR=\"llvm-ar\"" >> .mozconfig
 echo "export NM=\"llvm-nm\"" >> .mozconfig
@@ -742,6 +746,9 @@ gtk-update-icon-cache %{_datadir}/icons/hicolor &>/dev/null || :
 #===============================================================================
 
 %changelog
+* Fri Jul 05 2022 Tom Stellard <tstellar@redhat.com> - 91.11.0-2
+- Clean up macros that allow building with clang
+
 * Wed Jun 29 2022 Eike Rathke <erack@redhat.com> - 91.11.0-1
 - Update to 91.11.0