Initial creation of os_compat.h.

This creates a header for os_compat.c, and moves the related
prototypes into it from gpsd_config.h (as created by SConstruct),
after adding references to it to gpsd.h (via gpsd.h-tail) and a few
other sources that need it but don't include gpsd.h.

It also removes includes of <time.h> in the places where they were
only needed for the code now removed from gpsd_config.h.

TESTED:
Ran "scons build-all check" on OSX 10.9 (with strlcat/strlcpy but no
clock_gettime), OSX 10.12 (with strlcat/strlcpy and clock_gettime),
and Ubuntu 14 (with clock_gettime but no strlcat/strlcpy).  Also
verified that fallback versions were not being included where
unnecessary.

1 files changed, 1 insertions, 0 deletions

diff --git a/ppsthread.c b/ppsthread.c
index 53a93b2e..6aadf90d 100644
--- a/ppsthread.c
+++ b/ppsthread.c
@@ -84,6 +84,7 @@
 
 #include "timespec.h"
 #include "ppsthread.h"
+#include "os_compat.h"
 
 /*
  * Tell GCC that we want thread-safe behavior with _REENTRANT;