[build] fix build on MacOS X Tiger

See: https://trac.macports.org/ticket/58550
fixes for Tiger build, but can be applied generally to all builds
also requires legacysupport PortGroup for *at functions
kencu@macports.org

x-ref:
  https://trac.macports.org/ticket/58550
  https://github.com/macports/macports-ports/pull/4760

src/base.h

@@ -5,6 +5,12 @@
 #include <sys/types.h>
 #include <sys/time.h>
 
+#if defined(__APPLE__) && defined(__MACH__)
+#if __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ < 1050
+#include <time.h>
+#endif
+#endif
+
 #include "base_decls.h"
 #include "buffer.h"
 #include "array.h"

src/mod_webdav.c

@@ -2035,8 +2035,10 @@ webdav_prop_select_propnames (const plugin_config * const pconf,
 
 
 #if defined(__APPLE__) && defined(__MACH__)
+#if __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ >= 1050
 #include <copyfile.h>     /* fcopyfile() *//* OS X 10.5+ */
 #endif
+#endif
 #ifdef HAVE_ELFTC_COPYFILE/* __FreeBSD__ */
 #include <libelftc.h>     /* elftc_copyfile() */
 #endif
@@ -2068,12 +2070,14 @@ webdav_fcopyfile_sz (int ifd, int ofd, off_t isz)
   #endif
 
   #if defined(__APPLE__) && defined(__MACH__)
+  #if __ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__ >= 1050
     if (0 == fcopyfile(ifd, ofd, NULL, COPYFILE_ALL))
         return 0;
 
     if (0 != lseek(ifd, 0, SEEK_SET)) return -1;
     if (0 != lseek(ofd, 0, SEEK_SET)) return -1;
   #endif
+  #endif
 
   #ifdef HAVE_ELFTC_COPYFILE /* __FreeBSD__ */
     if (0 == elftc_copyfile(ifd, ofd))