Patch: Fix MIPS wrong code regression for java front-end.

[David Daney <ddaney at avtrex dot com>]

The java front-end is setting DECL_EXTERNAL properly for some symbols.  
This causes the MIPS back-end to generate incorrect function call code 
for the effected symbols.  According to the comments in:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30606

It seems that hpux is experiancing the same problem.

As noted in: http://gcc.gnu.org/ml/gcc/2007-02/msg00016.html

<quote>
The bad code was in class.c when green committed it over 8 years ago.  
Several months ago Tromey removed it and then added it back a few days 
later.

The problem is that in is_compiled_class() we were erroneously saying 
that a candidate class was being emitted to the object file *if* it was 
the current_class being parsed.  This does not hold because many classes 
are parsed that are not emitted so that jc1 can calculate the class 
layout and load the symbol tables.

The real fix,I think, is the one I made to is_compiled_class().  I left 
the change to layout_class_method() where we don't re-check for 
DECL_EXTERNAL if it is already set as a micro-optimization.  I tested 
both with and without this and obtained correct results, so it is not 
really needed.
</quote>

This fixes at least some of the MIPS regressions caused by the 
gcj-eclipse merge, also tested with a bootstrap of c,c++,java on 
x86_64-pc-linux-gnu with no regressions.

OK for the trunk?

gcc/java:
2007-02-01  David Daney  <ddaney@avtrex.com>

   * class.c (is_compiled_class): Move check to avoid reloading
   current class.
   (layout_class_method): Don't calculate DECL_EXTERNAL if it is
   already set.