readonly symbols and export symbols list

[Owen Taylor]

In http://bugzilla.gnome.org/show_bug.cgi?id=81232
there is a report that when using libtool with 
GCC and the Solaris linker, the -export-symbols-regex
option causes read only data symbols to never
be exported from the resulting object file, even
if they match the regex.

What seems to be the problem is that in 
AC_LIBTOOL_SYS_GLOBAL_SYMBOL_PIPE, a value of
[BDT] is used for $symcode on Solaris, but readonly 
data symbols will be 'R'.

So, when the list of symbols to export is determined,
the read-only data symbols will be missing and
the default 'local: *' in the linker script will
make them local.

Similarly, the GNU nm value should include 'R', 
though the effect of this currently is small; 
-export-symbols-regex doesn't do anything useful
for GNU ld and ELF.

(As noted elsewhere - it removes the symbols from the 
resulting object file, but doesn't do anything to the 
dynamic symbols that are actually used for linking.)

Regards,
                                        Owen

[ Thanks go to Alexandre Oliva for helping me track 
  this bug down via inspection of the libtool code. ]