* Makefile.am: Add support for installing crt1.o if one exists.
* configure.host: Specify crt1.o for linux.
* configure.in: Expose CRT1 and CRT1_DIR for Makefile.am to use.
* Makefile.in: Regenerated.
* configure: Ditto.
* libc/include/sys/unistd.h (_SC_STREAM_MAX, _SC_PRIORITY_SCHEDULING):
Added for non-Cygwin, non-RTEMS configurations.
* libc/sys/linux/Makefile.am: Add support for crt1 and sysconf.
* libc/sys/linux/Makefile.in: Regenerated.
* libc/sys/linux/crt1.c: New empty file to override one defaulted
by gcc. This fixes problem with reconfiguring linux newlib build.
* libc/sys/linux/sysconf.c: New file.