Removing AC_FUNC_ALLOCA from configure.in (added in the gnulib sync commit)

I added AC_FUNC_ALLOCA because of a mistake on my part (which has been fixed
before the final commit). Removing it now.

configure.in

@@ -47,7 +47,6 @@ AC_PROG_LIBTOOL
 AM_PROG_CC_C_O
 
 AC_FUNC_ERROR_AT_LINE
-AC_FUNC_ALLOCA
 AC_SYS_LARGEFILE
 
 ifdef([AC_FUNC_STRTOD],[AC_FUNC_STRTOD],[AM_FUNC_STRTOD])