[GDBserver] Fix SH/Linux build.

 sh-linux-gnu-gcc (...) src/gdb/gdbserver/linux-low.c
 .../src/gdb/gdbserver/linux-low.c: In function 'linux_read_loadmap':
 .../src/gdb/gdbserver/linux-low.c:5284:13: error: 'struct lwp_info' has no member named 'entry'
 make[1]: *** [linux-low.o] Error 1

gdb/gdbserver/
2014-04-09  Pedro Alves  <palves@redhat.com>

	* linux-low.c (linux_read_loadmap): Pass current_inferior directly
	to lwpid_of.