[CMake] Add -z defs on Solaris

[ro]

Summary

Like other ELF targets, shared objects should be linked with -z defs on Solaris.

Tested on x86_64-pc-solaris2.11 and sparcv9-sun-solaris2.11. Ok for trunk?

[ro]

Ping? It's been a week and this seems pretty obvious, bringing Solaris in line with other ELF targets.

[ro]

Ping^2? Two weeks now for a pretty obvious patch.

cmake/modules/HandleLLVMOptions.cmake

elseif(CMAKE_CXX_COMPILER_ID MATCHES "XL")
     # XL generates a small number of relocations not of the large model, -bbigtoc is needed.
     append("-Wl,-bbigtoc"
            CMAKE_EXE_LINKER_FLAGS CMAKE_MODULE_LINKER_FLAGS CMAKE_SHARED_LINKER_FLAGS)
   endif()
 endif()
 
 # Pass -Wl,-z,defs. This makes sure all symbols are defined. Otherwise a DSO
 # build might work on ELF but fail on MachO/COFF.
-if(NOT (${CMAKE_SYSTEM_NAME} MATCHES "Darwin|FreeBSD|OpenBSD|DragonFly|AIX" OR
+if(NOT (${CMAKE_SYSTEM_NAME} MATCHES "Darwin|FreeBSD|OpenBSD|DragonFly|AIX|SunOS" OR
         WIN32 OR CYGWIN) AND
    NOT LLVM_USE_SANITIZER)
   set(CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,-z,defs")
 endif()
 
 # Pass -Wl,-z,nodelete. This makes sure our shared libraries are not unloaded
 # by dlclose(). We need that since the CLI API relies on cross-references
 # between global objects which became horribly broken when one of the libraries