mips: remove stub entries from syscallent files, generate stubs at build time

* linux/mips/genstub.sh: New file.
* Makefile.am (EXTRA_DIST): Add it.
* configure.ac [MIPS]: Use it to generate syscallent stubs.
* linux/mips/.gitignore: Add syscallent stubs.
* linux/mips/syscallent-n32.h: Remove stub entries, include
the stub file instead.
* linux/mips/syscallent-n64.h: Likewise.
* linux/mips/syscallent-o32.h: Likewise.
7 files changed