* cygwin.sc: Use simpler method to align .cygheap.

* dllfixdbg: Just copy .stab and .stabstr sections when making cygwin1.dbg,
rather than relying on objcopy to keep only the debug sections since objcopy
seems to get it wrong.
* dtable.cc (build_fh_pc): Check setting fh to fhandler_nodevice for NULL, too.

winsup/cygwin/cygwin.sc

@@ -106,7 +106,7 @@ SECTIONS
   {
     __cygheap_mid = .;
     *(.cygheap)
-    . = ALIGN(512 * 1024, 0x10000);
+    . = ALIGN(512 * 1024);
   }
   __cygheap_end = ABSOLUTE(.);
   __cygheap_end1 = __cygheap_mid + SIZEOF(.cygheap);