Don't read symbol tables for .so's that constitute part of Valgrind

itself.  Doing so -- in this case for libc.so.6 -- confuses the
redirection machinery and so messes up redirections to
mac_replace_strmem.c, which in turn causes memcheck to report 
spurious errors.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@3356

coregrind/vg_memory.c

@@ -708,6 +708,7 @@ VG_(map_file_segment)( Addr addr, SizeT len,
       file, then try reading symbols from it.
    */
    if (s->symtab == NULL
+       && (addr+len < VG_(valgrind_base) || addr > VG_(valgrind_last))
        && (flags & (SF_MMAP|SF_NOSYMS)) == SF_MMAP) {
       if (off == 0
 	  && s->fnIdx != -1