compile: Fix function pointers

compile: Fix function pointers

TBH while I always comment reasons for each of the compilation options in
reality I tried them all and chose that combination that needs the most simple
compile/compile-object-load.c (ld.so emulation) implementation.

gdb/ChangeLog
2015-01-22  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* compile/compile.c (_initialize_compile): Use -fPIE for compile_args.

gdb/testsuite/ChangeLog
2015-01-22  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* gdb.compile/compile.exp (pointer to jit function): New test.