[Patch gas/mach-o] try to specify section flags better

[Iain Sandoe]

I found in some tests, that:
	align x
was causing the alignment padding to be zeroes - and thus broken.

This was caused by section definitions from GCC for various hot/cold/ 
startup etc. sections which are specified the long-hand way (rather  
than via a canonical name).

The solution is to  examine the incoming information and try to set  
the section flags from that, if possible.  This is adequate for the  
GCC output - but, in the general case it might be wise for people to  
write
	align x,<nop>

A similar scenario causes relocation problems if we don't recognize  
debug sections.

OK?
Iain


gas:
	* config/obj-macho.c (obj_mach_o_make_or_get_sect): In the absence of
	canonical information, try to determine CODE and DEBUG section flags
	from the mach-o section data.

--- gas/config/obj-macho.c	2012-02-12 15:42:47.000000000 +0000
+++ gas/config/obj-macho-b.c	2012-02-18 11:42:43.000000000 +0000
@@ -240,6 +240,16 @@ obj_mach_o_make_or_get_sect (char * segn

    if (oldflags == SEC_NO_FLAGS)
      {
+      if (flags == SEC_NO_FLAGS
+	  && (specified_mask & SECT_ATTR_SPECIFIED)
+	  && (secattr & BFD_MACH_O_S_ATTR_PURE_INSTRUCTIONS))
+	flags |= SEC_CODE;
+
+      if (flags == SEC_NO_FLAGS
+	  && (specified_mask & SECT_ATTR_SPECIFIED)
+	  && (secattr & BFD_MACH_O_S_ATTR_DEBUG))
+	flags |= SEC_DEBUGGING;
+
        /* New, so just use the defaults or what's specified.  */
        if (! bfd_set_section_flags (stdoutput, sec, flags))
  	as_warn (_("failed to set flags for \"%s\": %s"),