constify i386-sol2-tdep.c and machoread.c

constify i386-sol2-tdep.c and machoread.c

/home/pedro/gdb/mygit/src/gdb/i386-sol2-tdep.c: In function ‘const char* i386_sol2_static_transform_name(const char*)’:
/home/pedro/gdb/mygit/src/gdb/i386-sol2-tdep.c:93:29: error: invalid conversion from ‘const char*’ to ‘char*’ [-fpermissive]
       p = strrchr (name, '.');
                             ^
gdb:

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

	* i386-sol2-tdep.c (i386_sol2_static_transform_name): Move "p" to
	inner block and make it const.
	* machoread.c (get_archive_prefix_len): Make "lparen" const.