constify xcoffread.c

constify xcoffread.c

/home/pedro/gdb/mygit/src/gdb/xcoffread.c: In function ‘void scan_xcoff_symtab(objfile*)’:
/home/pedro/gdb/mygit/src/gdb/xcoffread.c:2644:33: error: invalid conversion from ‘const char*’ to ‘char*’ [-fpermissive]
      p = strchr (namestring, ':');
                                 ^
gdb:

2015-03-20  Pedro Alves  <palves@redhat.com>

	* xcoffread.c (scan_xcoff_symtab): Make "p" and "q" const.