fix x86-64 static codegen to materialize the address of a global with movl instead

fix x86-64 static codegen to materialize the address of a global with movl instead
of lea.  It is better for code size (and presumably efficiency) to use:

  movl $foo, %eax

rather than:

  leal foo, eax

Both give a nice zero extending "move immediate" instruction, the former is just
smaller.  Note that global addresses should be handled different by the x86
backend, but I chose to follow the style already in place and add more fixme's.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75403 91177308-0d34-0410-b5e6-96231b3b80d8