Add vendor macro to "lld"

[stevewan]

Summary

Add the vendor macro to "lld" for extended version output support,
such that it's able to print additional version info. This is
consistent with the Clang and LLVM version printer, and the
additional version message can be provided via PACKAGE_VENDOR.

[stevewan]

Fix format with 'clang-format'.

Pushed a wrong commit, please ignore this diff.

[stevewan]

Fix format with 'clang-format'.

[hubert.reinterpretcast]

This LGTM, but I'm not sure if people using PACKAGE_VENDOR for their builds are expecting this.

lld/CMakeLists.txt

Please install Python or specify the PYTHON_EXECUTABLE CMake variable.")
     endif()
   endif()
 endif()
 
 set(LLD_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
 set(LLD_INCLUDE_DIR ${LLD_SOURCE_DIR}/include )
 set(LLD_BINARY_DIR ${CMAKE_CURRENT_BINARY_DIR})
 
+set(LLD_VENDOR ${PACKAGE_VENDOR} CACHE STRING
+  "Vendor-specific text for showing with version information.")
+
+if(LLD_VENDOR)
+  add_definitions(-DLLD_VENDOR="${LLD_VENDOR}")
+endif()
+
 # Compute the LLD version from the LLVM version.
 string(REGEX MATCH "[0-9]+\\.[0-9]+(\\.[0-9]+)?" LLD_VERSION
   ${PACKAGE_VERSION})
 message(STATUS "LLD version: ${LLD_VERSION}")
 
 string(REGEX REPLACE "([0-9]+)\\.[0-9]+(\\.[0-9]+)?" "\\1" LLD_VERSION_MAJOR
   ${LLD_VERSION})
 string(REGEX REPLACE "[0-9]+\\.([0-9]+)(\\.[0-9]+)?" "\\1" LLD_VERSION_MINOR

lld/Common/Version.cpp

 
 #ifdef HAVE_VCS_VERSION_INC
 #include "VCSVersion.inc"
 #endif
 
 // Returns a version string, e.g.:
 // lld 9.0.0 (https://github.com/llvm/llvm-project.git 9efdd7ac5e914d3c9fa1ef)
 std::string lld::getLLDVersion() {
+#ifdef LLD_VENDOR
+#define LLD_VENDOR_DISPLAY LLD_VENDOR " "
+#else
+#define LLD_VENDOR_DISPLAY
+#endif
 #if defined(LLD_REPOSITORY) && defined(LLD_REVISION)
-  return "LLD " LLD_VERSION_STRING " (" LLD_REPOSITORY " " LLD_REVISION ")";
+  return LLD_VENDOR_DISPLAY "LLD " LLD_VERSION_STRING " (" LLD_REPOSITORY
+                            " " LLD_REVISION ")";
 #else
-  return "LLD " LLD_VERSION_STRING;
+  return LLD_VENDOR_DISPLAY "LLD " LLD_VERSION_STRING;
 #endif
+#undef LLD_VENDOR_DISPLAY
 }