[CMake] Add support for NO_INSTALL_RPATH argument in llvm_add_library()

[sgraenitz]

Summary

Allow clients to suppress setup of default RPATHs in designated library targets. This is used in LLDB when emitting liblldb as a framework bundle, which itself doesn't load further RPATH-dependent libraries.
This follows the approach in add_llvm_executable().

[aprantl]

cmake/modules/AddLLVM.cmake

458

Any kind of comment that we could add here that explains why this is happening? This looks quite mysterious to the casual reader otherwise :-)

[sgraenitz]

Add short comment for NO_INSTALL_RPATH parameter to function description

[sgraenitz]

cmake/modules/AddLLVM.cmake

458

Good point, thanks. Added short comment to the function description.

cmake/modules/AddLLVM.cmake

 #     May specify header files for IDE generators.
 #   SONAME
 #     Should set SONAME link flags and create symlinks
 #   PLUGIN_TOOL
 #     The tool (i.e. cmake target) that this plugin will link against
 #   )
 function(llvm_add_library name)
   cmake_parse_arguments(ARG
-    "MODULE;SHARED;STATIC;OBJECT;DISABLE_LLVM_LINK_LLVM_DYLIB;SONAME"
+    "MODULE;SHARED;STATIC;OBJECT;DISABLE_LLVM_LINK_LLVM_DYLIB;SONAME;NO_INSTALL_RPATH"
     "OUTPUT_NAME;PLUGIN_TOOL"
     "ADDITIONAL_HEADERS;DEPENDS;LINK_COMPONENTS;LINK_LIBS;OBJLIBS"
     ${ARGN})
   list(APPEND LLVM_COMMON_DEPENDS ${ARG_DEPENDS})
   if(ARG_ADDITIONAL_HEADERS)
     # Pass through ADDITIONAL_HEADERS.
     set(ARG_ADDITIONAL_HEADERS ADDITIONAL_HEADERS ${ARG_ADDITIONAL_HEADERS})
   endif()
llvm_add_library(${name_static} STATIC
       LINK_COMPONENTS ${ARG_LINK_COMPONENTS}
       )
     # FIXME: Add name_static to anywhere in TARGET ${name}'s PROPERTY.
     set(ARG_STATIC)
   endif()
 
   if(ARG_MODULE)
     add_library(${name} MODULE ${ALL_FILES})
-    llvm_setup_rpath(${name})
   elseif(ARG_SHARED)
     add_windows_version_resource_file(ALL_FILES ${ALL_FILES})
     add_library(${name} SHARED ${ALL_FILES})
-
-    llvm_setup_rpath(${name})
-
   else()
     add_library(${name} STATIC ${ALL_FILES})
   endif()
 
+  if(NOT ARG_NO_INSTALL_RPATH)
+    if(ARG_MODULE OR ARG_SHARED)
+      llvm_setup_rpath(${name})
+    endif()
+  endif()
+
   setup_dependency_debugging(${name} ${LLVM_COMMON_DEPENDS})
 
   if(DEFINED windows_resource_file)
     set_windows_version_resource_properties(${name} ${windows_resource_file})
     set(windows_resource_file ${windows_resource_file} PARENT_SCOPE)
   endif()
 
   set_output_directory(${name} BINARY_DIR ${LLVM_RUNTIME_OUTPUT_INTDIR} LIBRARY_DIR ${LLVM_LIBRARY_OUTPUT_INTDIR})