[build] add the ability to create a symlink for lipo

[anushabasana]

Summary

Add user enabled option to create lipo with symlink to llvm-lipo
Used rL326381 for reference.

[smeenai]

LGTM

llvm/trunk/CMakeLists.txt

 
 # Generate a CompilationDatabase (compile_commands.json file) for our build,
 # for use by clang_complete, YouCompleteMe, etc.
 set(CMAKE_EXPORT_COMPILE_COMMANDS 1)
 
 option(LLVM_INSTALL_BINUTILS_SYMLINKS
   "Install symlinks from the binutils tool names to the corresponding LLVM tools." OFF)
 
+option(LLVM_INSTALL_CCTOOLS_SYMLINKS
+  "Install symlinks from the cctools tool names to the corresponding LLVM tools." OFF)
+
 option(LLVM_INSTALL_UTILS "Include utility binaries in the 'install' target." OFF)
 
 option(LLVM_INSTALL_TOOLCHAIN_ONLY "Only include toolchain files in the 'install' target." OFF)
 
 # Unfortunatly Clang is too eager to search directories for module maps, which can cause the
 # installed version of the maps to be found when building LLVM from source. Therefore we turn off
 # the installation by default. See llvm.org/PR31905.
 option(LLVM_INSTALL_MODULEMAPS "Install the modulemap files in the 'install' target." OFF)

llvm/trunk/docs/CMake.rst

 **LLVM_INCLUDE_TOOLS**:BOOL
   Generate build targets for the LLVM tools. Defaults to ON. You can use this
   option to disable the generation of build targets for the LLVM tools.
 
 **LLVM_INSTALL_BINUTILS_SYMLINKS**:BOOL
   Install symlinks from the binutils tool names to the corresponding LLVM tools.
   For example, ar will be symlinked to llvm-ar.
 
+**LLVM_INSTALL_CCTOOLS_SYMLINKS**:BOOL
+  Install symliks from the cctools tool names to the corresponding LLVM tools.
+  For example, lipo will be symlinked to llvm-lipo.
+
 **LLVM_BUILD_EXAMPLES**:BOOL
   Build LLVM examples. Defaults to OFF. Targets for building each example are
   generated in any case. See documentation for *LLVM_BUILD_TOOLS* above for more
   details.
 
 **LLVM_INCLUDE_EXAMPLES**:BOOL
   Generate build targets for the LLVM examples. Defaults to ON. You can use this
   option to disable the generation of build targets for the LLVM examples.

llvm/trunk/tools/llvm-lipo/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
   ${LLVM_TARGETS_TO_BUILD}
   Object
   Option
   Support
 )
 
 set(LLVM_TARGET_DEFINITIONS LipoOpts.td)
 tablegen(LLVM LipoOpts.inc -gen-opt-parser-defs)
 add_public_tablegen_target(LipoOptsTableGen)
 
 add_llvm_tool(llvm-lipo
   llvm-lipo.cpp
   DEPENDS
   LipoOptsTableGen
 )
+
+if(LLVM_INSTALL_CCTOOLS_SYMLINKS)
+  add_llvm_tool_symlink(lipo llvm-lipo)
+endif()