* gdb.dwarf2/watch-notconst.exp: Use is_x86_like_target.
* gdb.dwarf2/valop.exp: Use is_x86_like_target.
* gdb.dwarf2/typeddwarf.exp: Use is_x86_like_target. Pass
-nostdlib to compiler.
* gdb.dwarf2/typeddwarf.S (_start): Rename from 'main'.
* gdb.dwarf2/pieces.exp: Use is_x86_like_target.
* gdb.dwarf2/implptr.exp: Use is_x86_like_target.
* gdb.dwarf2/dw2-restore.exp: Check for LP64.
* gdb.dwarf2/callframecfa.exp: Use is_x86_like_target.