shell: do not play duplicated definition games to shrink the executable

Playing with linker games to shrink git-shell did not go well with various
other platforms and compilers.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

shell.c

@@ -3,14 +3,6 @@
 #include "exec_cmd.h"
 #include "strbuf.h"
 
-/* Stubs for functions that make no sense for git-shell. These stubs
- * are provided here to avoid linking in external redundant modules.
- */
-void release_pack_memory(size_t need, int fd){}
-void trace_argv_printf(const char **argv, const char *fmt, ...){}
-void trace_printf(const char *fmt, ...){}
-
-
 static int do_generic_cmd(const char *me, char *arg)
 {
 	const char *my_argv[4];