apply: move libified code from builtin/apply.c to apply.{c,h}

As most of the apply code in builtin/apply.c has been libified by a number of
previous commits, it can now be moved to apply.{c,h}, so that more code can
use it.

Helped-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Helped-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

apply.h

@@ -102,6 +102,20 @@ extern int parse_whitespace_option(struct apply_state *state,
 extern int parse_ignorewhitespace_option(struct apply_state *state,
 					 const char *option);
 
+extern int apply_option_parse_exclude(const struct option *opt,
+				      const char *arg, int unset);
+extern int apply_option_parse_include(const struct option *opt,
+				      const char *arg, int unset);
+extern int apply_option_parse_p(const struct option *opt,
+				const char *arg,
+				int unset);
+extern int apply_option_parse_whitespace(const struct option *opt,
+					 const char *arg, int unset);
+extern int apply_option_parse_directory(const struct option *opt,
+					const char *arg, int unset);
+extern int apply_option_parse_space_change(const struct option *opt,
+					   const char *arg, int unset);
+
 extern int init_apply_state(struct apply_state *state,
 			    const char *prefix,
 			    struct lock_file *lock_file);
@@ -115,4 +129,9 @@ extern int check_apply_state(struct apply_state *state, int force_apply);
 #define APPLY_OPT_INACCURATE_EOF	(1<<0) /* accept inaccurate eof */
 #define APPLY_OPT_RECOUNT		(1<<1) /* accept inaccurate line count */
 
+extern int apply_all_patches(struct apply_state *state,
+			     int argc,
+			     const char **argv,
+			     int options);
+
 #endif