LoongArch: Fix redefinition of "PACKAGE".

  Running configure and make in binutils-gdb.

  $ ./configure
  $ make
In file included from ./as.h:37,
                 from ./config/loongarch-lex.l:21,
                 from config/loongarch-lex-wrapper.c:20:
./config.h:206: error: “PACKAGE” redefined [-Werror]
 #define PACKAGE "gas"
...

  gas/config
  *  loongarch-lex-wrapper.c
1 file changed