build: fix enable/disable language in ./configure --help

Based on patch from Brian Paul.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=32317
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

acinclude.m4

@@ -17,7 +17,7 @@ AC_DEFUN([MESA_PIC_FLAGS],
 AC_ARG_VAR([PIC_FLAGS], [compiler flags for PIC code])
 AC_ARG_ENABLE([pic],
     [AS_HELP_STRING([--disable-pic],
-        [compile PIC objects @<:@default=enabled for shared builds
+        [don't compile PIC objects @<:@default=enabled for shared builds
         on supported platforms@:>@])],
     [enable_pic="$enableval"
     test "x$enable_pic" = x && enable_pic=auto],

configure.ac

@@ -877,7 +877,7 @@ cygwin*)
 esac
 AC_ARG_ENABLE([driglx-direct],
     [AS_HELP_STRING([--disable-driglx-direct],
-        [enable direct rendering in GLX and EGL for DRI \
+        [disable direct rendering in GLX and EGL for DRI \
             @<:@default=auto@:>@])],
     [driglx_direct="$enableval"],
     [driglx_direct="$driglx_direct_default"])