[CMake] Enable -z defs on Solaris

[ro]

Summary

I wondered why I hadn't seen the link failures in D130571 on Solaris/sparcv9 and found that Solaris, unlike Linux, doesn't use -Wl,-z,defs when linking shared objects. The three affected shared objects indeed have undefined references to several 64-bit atomics.

This patch will expose such issues in the future by defaulting to -Wl,-z,defs on Solaris, as recommended in ld(1).

Tested on sparcv9-sun-solaris2.11 and amd64-pc-solaris2.11.

llvm/cmake/modules/HandleLLVMOptions.cmake

if(BUILD_SHARED_LIBS)
     # See rpath handling in AddLLVM.cmake
     # FIXME: Remove this warning if this rpath is no longer hardcoded.
     message(WARNING "Build and install environment path info may be exposed; binaries will also be unrelocatable.")
   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|SunOS|OS390" OR
+if(NOT (CMAKE_SYSTEM_NAME MATCHES "Darwin|FreeBSD|OpenBSD|DragonFly|AIX|OS390" 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