[core] Remove deprecated macOS linker flag(s)

ld: warning: -bind_at_load is deprecated on macOS

From $ man ld:
Sets a bit in the mach header of the resulting binary which tells dyld
to bind all symbols when the binary is loaded, rather than lazily.

This contradicts the flags RTLD_LAZY|RTLD_LOCAL passed to dlopen
when loading libCling, and is different from the behavior on other
platforms that don't have this flag, such as Linux.

Also remove the warning suppression that was hiding this deprecation
message. It was added as part of commit 5ad4ab9 ("[cmake] Silence
macOS linker warnings on -undefined dynamic_lookup:"), which we don't
use anymore for libCling since the previous commit.

Author: hahnjo

core/metacling/src/CMakeLists.txt

@@ -221,9 +221,7 @@ if(MSVC)
   set_property(TARGET Cling APPEND_STRING PROPERTY LINK_FLAGS "${cling_link_str} ${CLAD_LIBS}")
 endif()
 
-if(APPLE)
-  target_link_libraries(Cling PRIVATE -Wl,-w -Wl,-bind_at_load)
-elseif(NOT MSVC)
+if(NOT APPLE AND NOT MSVC)
   # Require the linker to resolve the symbol internally and prevent
   # conflicts when linked with another software using also LLVM like in
   # the problem reported for Julia in