Fix parallel "make install" on MS-Windows.

Fix parallel "make install" on MS-Windows.

 nt/makefile.w32-in (install-bin): Don't copy addpm.exe here.  Use
 $(DIRNAME)_same-dir.tst instead of same-dir.tst, to avoid stepping
 on other (parallel) Make job's toes.
 (install-other-dirs-nmake, install-other-dirs-gmake): Depend on `all'.
 (install-shortcuts): Depend on $(INSTALL_DIR)/bin.  Copy addpm.exe
 here.
 (maybe-copy-distfiles-CMD, maybe-copy-distfiles-SH, dist): Depend
 on create-tmp-dist-dir.
 nt/nmake.defs (DIRNAME): New variable.
 (IFNOTSAMEDIR): Use $(DIRNAME)_same-dir.tst instead of
 same-dir.tst.
 nt/gmake.defs (DIRNAME): New variable.
 (IFNOTSAMEDIR): Use $(DIRNAME)_same-dir.tst instead of
 same-dir.tst, to avoid conflicts between several (parallel) Make
 jobs.
 lisp/makefile.w32-in (install): Use $(DIRNAME)_same-dir.tst instead
 of same-dir.tst, to avoid stepping on other (parallel) Make job's
 toes.
 leim/makefile.w32-in (install): Use $(DIRNAME)_same-dir.tst instead
 of same-dir.tst, to avoid stepping on other (parallel) Make job's
 toes.