Don't assume that egrep and fgrep exist, as POSIX 1003.1-2001 no
longer requires them.
* Makefile.am (maintainer-check): Use grep -E and grep -F instead
of egrep and fgrep. Omit unnecessary -E and -F.
Fix quoting typo -- "fgrep '\$${'" should have been "fgrep '$${'".
* lib/am/distdir.am (distdir): fgrep -> grep -F.
Use $(), not ${}, for Make variables.
* lib/am/texinfos.am (install-info-am, uninstall-info-am):
fgrep -> grep
* m4/make.m4 (AM_MAKE_INCLUDE): Likewise.
* tests/defs: Set FGREP and EGREP.