deskutils/subsurface: Fix build on older FreeBSD versions

On FreeBSD 12.3, build fail with:

In file included from /wrkdirs/usr/ports/deskutils/subsurface/work/subsurface-5.0.10/core/exif.cpp:32:
/wrkdirs/usr/ports/deskutils/subsurface/work/subsurface-5.0.10/core/exif.h:128:3: error: unknown type name 'time_t'
  time_t epoch();
        ^
1 error generated.

Explicitly add time.h to headers which use time_t to avoid the issue.
This should not have an impact where the package could be build so not
bumping PORTREVISION.

deskutils/subsurface/files/patch-core_exif.h

@@ -0,0 +1,10 @@
+--- core/exif.h.orig	2022-12-19 04:30:05 UTC
++++ core/exif.h
+@@ -36,6 +36,7 @@
+ #define __EXIF_H
+ 
+ #include <string>
++#include <time.h>
+ 
+ namespace easyexif {
+ 

deskutils/subsurface/files/patch-core_parse-gpx.h

@@ -0,0 +1,10 @@
+--- core/parse-gpx.h.orig	2022-12-19 05:04:53 UTC
++++ core/parse-gpx.h
+@@ -3,6 +3,7 @@
+ #define PARSE_GPX_H
+ 
+ #include <QString>
++#include <time.h>
+ 
+ struct dive_coords {         // This structure holds important information after parsing the GPX file:
+ 	time_t start_dive;            // Start time of the current dive, obtained using current_dive (local time)