* guix.scm (%source-dir): New variable.
(git-file?): New function.
(mes): Use them to simplify building/installing from git.
* make/install.make (READMES): Add INSTALL, README.
* (install): Install mescc.scm and read-0-32.mo.
* module/language/c99/compiler.mes: New file.
* module/language/c99/compiler.scm: Include it.
* module/mes/elf.mes: Move (mes-use-module) into cond-expand.
* module/mes/elf.scm: New file.
* module/mes/libc-i386.scm: New file.
* module/nyacc/lang/c99/parser.mes: Add missing module includes.
* module/nyacc/lang/util.mes: Add missing module include.
* scripts/mescc.mes: Use Nyacc.
* guile/mescc.scm: New file.
* GNUmakefile (guile-mescc): Run it.