This ensures we use the same method in "make" as in "guix/self.scm".
* Makefile.am: Build guix/build/po.scm.
* build-aux/convert-xref.scm: New file.
* doc/local.mk (xref_command): Use it.
* guix/self.scm (translate-cross-references): Move it...
* guix/build/po.scm: Parse comments and flags separately to find fuzzy
flags.
(translate-cross-references): ...here.
(parse-tree->assoc): Ignore fuzzy entries.
This reduces the execution time of:
(call-with-input-file "po/doc/guix-manual.de.po" read-po-file)
from 4.7s to 4.0s.
* guix/build/po.scm (interpret-newline-escape): New procedure.
(parse-tree->assoc): Use it instead of 'regexp-substitute/global'.
* guix/self.scm (info-manual): Run po4a and related commands to generate
translated texi files before building translated manuals.
* guix/build/po.scm: New file.
* Makefile.am (MODULES_NOT_COMPILED): Add it.
