[clang] Create install targets for non-shared libraries

[smeenai]

Summary

I don't see a reason for these to not have install targets created,
which in turn allows them to be bundled in distributions. This doesn't
affect the "install" target, since that just runs all CMake install
rules (and we were already creating install rules for these).

[phosek]

LGTM

cmake/modules/AddClang.cmake

if (NOT LLVM_INSTALL_TOOLCHAIN_ONLY OR ${name} STREQUAL "libclang")
 
       install(TARGETS ${name}
         COMPONENT ${name}
         ${export_to_clangtargets}
         LIBRARY DESTINATION lib${LLVM_LIBDIR_SUFFIX}
         ARCHIVE DESTINATION lib${LLVM_LIBDIR_SUFFIX}
         RUNTIME DESTINATION bin)
 
-      if (${ARG_SHARED} AND NOT CMAKE_CONFIGURATION_TYPES)
+      if (NOT CMAKE_CONFIGURATION_TYPES)
         add_llvm_install_targets(install-${name}
                                  DEPENDS ${name}
                                  COMPONENT ${name})
       endif()
     endif()
     set_property(GLOBAL APPEND PROPERTY CLANG_EXPORTS ${name})
   else()
     # Add empty "phony" target