Switch to indentation by space, not tab.

Switch to indentation by space, not tab.

Now that gnulib has converted and git has better support for
ignoring whitespace differences across this commit, we might as
well be consistent with other GNU projects.

Done with:
t=$'\t'
git ls-files \
  | grep -vE '(^|/)(.*akefile|ChangeLog|HACKING|.*-aux/.*)|\.(am|mk)$' \
  | xargs grep -lE "^ *$t" \
  | xargs perl -MText::Tabs -ni -le \
    '$m=/^( *\t[ \t]*)(.*)/; print $m ? expand($1) . $2 : $_'

followed by tweaks to pass 'make check' again.

* .gitmodules: Convert leading tabs to spaces.
* TODO: Likewise.
* bootstrap: Likewise.
* configure.ac: Likewise.
* examples/WWW/m4lib/html.m4: Likewise.
* examples/WWW/m4lib/layout.m4: Likewise.
* examples/WWW/m4lib/menu.m4: Likewise.
* ltdl/m4/debug.m4: Likewise.
* ltdl/m4/gmp.m4: Likewise.
* ltdl/m4/m4-obstack.m4: Likewise.
* ltdl/m4/stackovf.m4: Likewise.
* m4/builtin.c: Likewise.
* m4/debug.c: Likewise.
* m4/hash.c: Likewise.
* m4/hash.h: Likewise.
* m4/input.c: Likewise.
* m4/m4.c: Likewise.
* m4/m4module.h: Likewise.
* m4/m4private.h: Likewise.
* m4/macro.c: Likewise.
* m4/module.c: Likewise.
* m4/output.c: Likewise.
* m4/path.c: Likewise.
* m4/resyntax.c: Likewise.
* m4/symtab.c: Likewise.
* m4/syntax.c: Likewise.
* m4/utility.c: Likewise.
* modules/evalparse.c: Likewise.
* modules/format.c: Likewise.
* modules/gnu.c: Likewise.
* modules/load.c: Likewise.
* modules/m4.c: Likewise.
* modules/m4.h: Likewise.
* modules/mpeval.c: Likewise.
* modules/perl.c: Likewise.
* modules/stdlib.c: Likewise.
* modules/time.c: Likewise.
* src/freeze.c: Likewise.
* src/m4.h: Likewise.
* src/main.c: Likewise.
* src/stackovf.c: Likewise.
* tests/builtins.at: Likewise.
* tests/freeze.at: Likewise.
* tests/generate.awk: Likewise.
* tests/modules.at: Likewise.
* tests/others.at: Likewise.
* tests/stackovf.test: Likewise.
* tests/testsuite.at: Likewise.

Signed-off-by: Eric Blake <ebb9@byu.net>
(cherry picked from commit 180b7d19bf95d2abb21bca587a0684eca69679ad)