Re: aclocal.m4: Update PKG_* macros to pkg-config 0.29.2 (issue 551590044 by address@hidden)

[lemzwerg]

Reviewers: hanwenn, hahnjo,

Message:
> > can we include this rather than copy & paste?
> 
> This would require generating aclocal.m4 by aclocal as 
> part of generating configure. I'm all for doing this,
> but I'd avoid doing this level of tooling changes
> before 2.21.0

Seconded.

Description:
aclocal.m4: Update PKG_* macros to pkg-config 0.29.2

This commit removes the old definition of PKG_CHECK_MODULES (from 2004)
and
simply appends a recent version of pkg-config's file `pkg.m4` at the end
of
`aclocal.m4`.

This immediately improves documentation of pkg-config stuff.  Now the
list
of environment variables shown in `configure --help` ends with

  PKG_CONFIG  path to pkg-config utility
  PKG_CONFIG_PATH
              directories to add to pkg-config's search path
  PKG_CONFIG_LIBDIR
              path overriding pkg-config's built-in search path
  GUILE_CFLAGS
              C compiler flags for GUILE, overriding pkg-config
  GUILE_LIBS  linker flags for GUILE, overriding pkg-config
  BDWGC_CFLAGS
              C compiler flags for BDWGC, overriding pkg-config
  BDWGC_LIBS  linker flags for BDWGC, overriding pkg-config
  PANGO_FT2_CFLAGS
              C compiler flags for PANGO_FT2, overriding pkg-config
  PANGO_FT2_LIBS
              linker flags for PANGO_FT2, overriding pkg-config
  FONTCONFIG_CFLAGS
              C compiler flags for FONTCONFIG, overriding pkg-config
  FONTCONFIG_LIBS
              linker flags for FONTCONFIG, overriding pkg-config
  FREETYPE2_CFLAGS
              C compiler flags for FREETYPE2, overriding pkg-config
  FREETYPE2_LIBS
              linker flags for FREETYPE2, overriding pkg-config
  GLIB_CFLAGS C compiler flags for GLIB, overriding pkg-config
  GLIB_LIBS   linker flags for GLIB, overriding pkg-config
  GOBJECT_CFLAGS
              C compiler flags for GOBJECT, overriding pkg-config
  GOBJECT_LIBS
              linker flags for GOBJECT, overriding pkg-config

Please review this at https://codereview.appspot.com/551590044/

Affected files (+277, -54 lines):
  M aclocal.m4