* dwarf2dbg.c (dwarf2dbg_final_check): Rename local variable exp from expr.

* dwarf2dbg.c (dwarf2dbg_final_check): Rename local variable exp from expr.

Trying to build (for mmix-knuth-mmixware but I don't think that
matters) yields the following (repeatable on e.g. CompileFarm gcc20
sporting gcc-4.7.2 as default):

gcc -DHAVE_CONFIG_H -I. -I/home/hp/binutils/src/gas  -I. -I/home/hp/binutils/src/gas -I../bfd -I/home/hp/binutils/src/gas/config -I/home/hp/binutils/src/gas/../include -I/home/hp/binutils/src/gas/.. -I/home/hp/binutils/src/gas/../bfd -DLOCALEDIR="\"/usr/local/share/locale\""  -W -Wall -Wstrict-prototypes -Wmissing-prototypes -Wshadow -Werror -Wwrite-strings -I/home/hp/binutils/src/gas/../zlib -g -O2 -MT dwarf2dbg.o -MD -MP -MF .deps/dwarf2dbg.Tpo -c -o dwarf2dbg.o /home/hp/binutils/src/gas/dwarf2dbg.c
cc1: warnings being treated as errors
/home/hp/binutils/src/gas/dwarf2dbg.c: In function 'dwarf2dbg_final_check':
/home/hp/binutils/src/gas/dwarf2dbg.c:2246: error: declaration of 'expr' shadows a global declaration
/home/hp/binutils/src/gas/expr.h:180: error: shadowed declaration is here
make[4]: *** [dwarf2dbg.o] Error 1

IIRC this is a false namespace clash and the warning is not observable
with a new-enough gcc.  Committed as obvious.

brgds, H-P
PS. Idea: -Wcompiler; warn about constructs problematic with e.g. old gcc. 1/2 ;-)