Minor nsfont.m fix

Since we do not expect NULL from xmalloc and xzalloc, some redundant checks
may be omitted, OK?

Dmitry

=== modified file 'src/nsfont.m'
--- src/nsfont.m	2012-07-13 18:03:10 +0000
+++ src/nsfont.m	2012-08-15 13:48:52 +0000
 <at>  <at>  -1292,8 +1292,6  <at>  <at> 
 #endif

   font_info->glyphs[block] = xmalloc (0x100 * sizeof (unsigned short));
-  if (!unichars || !(font_info->glyphs[block]))
-    abort ();

   /* create a string containing all Unicode characters in this block */
   for (idx = block<<8, i = 0; i < 0x100; idx++, i++)
 <at>  <at>  -1367,8 +1365,6  <at>  <at> 
  sfont = [font_info->nsfont screenFont];

   font_info->metrics[block] = xzalloc (0x100 * sizeof (struct font_metrics));
-  if (!(font_info->metrics[block]))
-    abort ();

   metrics = font_info->metrics[block];
   for (g = block<<8, i =0; i<0x100 && g < numGlyphs; g++, i++, metrics++)