Set linker-related things with configure.

Set linker-related things with configure.

* configure.in (LINKER, YMF_PASS_LDFLAGS): New output variables.
(ORDINARY_LINK): New AC_DEFINE.
(LIB_GCC): No need to set if ORDINARY_LINK.

* src/Makefile.in (LD, YMF_PASS_LDFLAGS): Set with configure, not cpp.
(GNULIB_VAR): Remove.
(LIBES): Use LIB_GCC instead of GNULIB_VAR.

* src/m/ibms390x.h (LINKER):
* src/m/macppc.h (LINKER) [GNU_LINUX]:
* src/s/aix4-2.h (ORDINARY_LINK):
* src/s/cygwin.h (LINKER):
* src/s/darwin.h (ORDINARY_LINK):
* src/s/gnu.h (ORDINARY_LINK):
* src/s/netbsd.h (LINKER):
* src/s/usg5-4.h (ORDINARY_LINK):
Move to configure.

* msdos/sed1v2.inp (LD): Edit to $(CC).
(YMF_PASS_LDFLAGS): Edit to `flags'.