Initialize variables in i386_linux_handle_segmentation_fault

We see this error when building with gcc 4.3.

../../gdb/i386-linux-tdep.c: In function ‘i386_linux_handle_segmentation_fault’:
../../gdb/i386-linux-tdep.c:399: error: ‘access’ may be used uninitialized in this function
../../gdb/i386-linux-tdep.c:399: error: ‘upper_bound’ may be used uninitialized in this function
../../gdb/i386-linux-tdep.c:399: error: ‘lower_bound’ may be used uninitialized in this function

It's a false positive, since the variables will always get initialized
in the TRY clause, and the CATCH returns.

gdb/ChangeLog:

	* i386-linux-tdep.c (i386_linux_handle_segmentation_fault):
	Initialize variables.