Improve Gnulib's ability to compile on FreeBSD

[Tom Limoncelli]

I can't take credit for this... it comes from:
https://svn.csub.edu/p/freebsd/browser/freebsd/ports/trunk/textproc/augeas/files/patch-gnulib%3A%3Alib%3A%3AMakefile.am?rev=73

--- gnulib/lib/Makefile.am.orig 2010-04-28 14:46:00.000000000 -0700
+++ gnulib/lib/Makefile.am      2010-04-28 14:47:00.000000000 -0700
@@ -395,7 +395,7 @@
          case '$(host_os)' in \
            darwin[56]*) \
              need_charset_alias=true ;; \
-           darwin* | cygwin* | mingw* | pw32* | cegcc*) \
+           darwin* | cygwin* | mingw* | pw32* | cegcc* | freebsd*) \
              need_charset_alias=false ;; \
            *) \
              need_charset_alias=true ;; \