Move some declarations to source.h

I noticed a few declarations in defs.h that really could be put into
source.h.  I think it's generally preferable to something out of
defs.h unless it is needed by most of the files in gdb.

gdb/ChangeLog
2018-02-14  Tom Tromey  <tom@tromey.com>

	* solib.c: Include source.h.
	* nto-tdep.c: Include source.h.
	* mi/mi-cmd-env.c: Include source.h.
	* infcmd.c: Include source.h.
	* exec.c: Include source.h.
	* defs.h (enum openp_flag, openp, source_full_path_of, mod_path)
	(add_path, directory_switch, source_path, init_source_path): Move
	declarations...
	* source.h (enum openp_flag, openp, source_full_path_of, mod_path)
	(add_path, directory_switch, source_path, init_source_path):
	...here.

gdb/ChangeLog

@@ -1,3 +1,17 @@
+2018-02-14  Tom Tromey  <tom@tromey.com>
+
+	* solib.c: Include source.h.
+	* nto-tdep.c: Include source.h.
+	* mi/mi-cmd-env.c: Include source.h.
+	* infcmd.c: Include source.h.
+	* exec.c: Include source.h.
+	* defs.h (enum openp_flag, openp, source_full_path_of, mod_path)
+	(add_path, directory_switch, source_path, init_source_path): Move
+	declarations...
+	* source.h (enum openp_flag, openp, source_full_path_of, mod_path)
+	(add_path, directory_switch, source_path, init_source_path):
+	...here.
+
 2018-02-14  Tom Tromey  <tom@tromey.com>
 
 	* solist.h (exec_file_find, solib_find): Return

gdb/defs.h

@@ -339,33 +339,6 @@ extern int build_address_symbolic (struct gdbarch *,
 extern void print_address (struct gdbarch *, CORE_ADDR, struct ui_file *);
 extern const char *pc_prefix (CORE_ADDR);
 
-/* From source.c */
-
-/* See openp function definition for their description.  */
-
-enum openp_flag
-{
-  OPF_TRY_CWD_FIRST = 0x01,
-  OPF_SEARCH_IN_PATH = 0x02,
-  OPF_RETURN_REALPATH = 0x04,
-};
-
-DEF_ENUM_FLAGS_TYPE(openp_flag, openp_flags);
-
-extern int openp (const char *, openp_flags, const char *, int, char **);
-
-extern int source_full_path_of (const char *, char **);
-
-extern void mod_path (const char *, char **);
-
-extern void add_path (const char *, char **, int);
-
-extern void directory_switch (const char *, int);
-
-extern char *source_path;
-
-extern void init_source_path (void);
-
 /* From exec.c */
 
 /* * Process memory area starting at ADDR with length SIZE.  Area is

gdb/exec.c

@@ -35,6 +35,7 @@
 #include "progspace.h"
 #include "gdb_bfd.h"
 #include "gcore.h"
+#include "source.h"
 
 #include <fcntl.h>
 #include "readline/readline.h"

gdb/infcmd.c

@@ -59,6 +59,7 @@
 #include "top.h"
 #include "interps.h"
 #include "common/gdb_optional.h"
+#include "source.h"
 
 /* Local functions: */
 

gdb/mi/mi-cmd-env.c

@@ -31,6 +31,7 @@
 #include "ui-out.h"
 #include "top.h"
 #include <sys/stat.h>
+#include "source.h"
 
 static const char path_var_name[] = "PATH";
 static char *orig_path = NULL;

gdb/nto-tdep.c

@@ -31,6 +31,7 @@
 #include "solib-svr4.h"
 #include "gdbcore.h"
 #include "objfiles.h"
+#include "source.h"
 
 #define QNX_NOTE_NAME	"QNX"
 #define QNX_INFO_SECT_NAME "QNX_info"

gdb/solib.c

@@ -46,6 +46,7 @@
 #include "filesystem.h"
 #include "gdb_bfd.h"
 #include "filestuff.h"
+#include "source.h"
 
 /* Architecture-specific operations.  */
 

gdb/source.h

@@ -21,6 +21,31 @@
 
 struct symtab;
 
+/* See openp function definition for their description.  */
+
+enum openp_flag
+{
+  OPF_TRY_CWD_FIRST = 0x01,
+  OPF_SEARCH_IN_PATH = 0x02,
+  OPF_RETURN_REALPATH = 0x04,
+};
+
+DEF_ENUM_FLAGS_TYPE(openp_flag, openp_flags);
+
+extern int openp (const char *, openp_flags, const char *, int, char **);
+
+extern int source_full_path_of (const char *, char **);
+
+extern void mod_path (const char *, char **);
+
+extern void add_path (const char *, char **, int);
+
+extern void directory_switch (const char *, int);
+
+extern char *source_path;
+
+extern void init_source_path (void);
+
 /* This function is capable of finding the absolute path to a
    source file, and opening it, provided you give it a FILENAME.  Both the
    DIRNAME and FULLNAME are only added suggestions on where to find the file.