cmake: move nanosecond detection to a module

Move the nanosecond detection in time structures to its own module.

CMakeLists.txt

@@ -31,6 +31,7 @@ INCLUDE(CheckStructHasMember)
 INCLUDE(AddCFlagIfSupported)
 INCLUDE(FindPkgConfig)
 INCLUDE(FindThreads)
+INCLUDE(FindStatNsec)
 INCLUDE(FeatureSummary)
 
 # Build options
@@ -94,27 +95,6 @@ IF(MSVC)
 	OPTION(MSVC_CRTDBG "Enable CRTDBG memory leak reporting" OFF)
 ENDIF()
 
-CHECK_STRUCT_HAS_MEMBER ("struct stat" st_mtim "sys/types.h;sys/stat.h"
-	HAVE_STRUCT_STAT_ST_MTIM LANGUAGE C)
-CHECK_STRUCT_HAS_MEMBER ("struct stat" st_mtimespec "sys/types.h;sys/stat.h"
-	HAVE_STRUCT_STAT_ST_MTIMESPEC LANGUAGE C)
-CHECK_STRUCT_HAS_MEMBER("struct stat" st_mtime_nsec sys/stat.h
-	HAVE_STRUCT_STAT_MTIME_NSEC LANGUAGE C)
-
-IF (HAVE_STRUCT_STAT_ST_MTIM)
-	CHECK_STRUCT_HAS_MEMBER("struct stat" st_mtim.tv_nsec sys/stat.h
-		HAVE_STRUCT_STAT_NSEC LANGUAGE C)
-ELSEIF (HAVE_STRUCT_STAT_ST_MTIMESPEC)
-	CHECK_STRUCT_HAS_MEMBER("struct stat" st_mtimespec.tv_nsec sys/stat.h
-		HAVE_STRUCT_STAT_NSEC LANGUAGE C)
-ELSE ()
-	SET( HAVE_STRUCT_STAT_NSEC ON )
-ENDIF()
-
-IF (HAVE_STRUCT_STAT_NSEC OR WIN32)
-	OPTION( USE_NSEC		"Care about sub-second file mtimes and ctimes"	ON  )
-ENDIF()
-
 # This function splits the sources files up into their appropriate
 # subdirectories.  This is especially useful for IDEs like Xcode and
 # Visual Studio, so that you can navigate into the libgit2_clar project,

cmake/Modules/FindStatNsec.cmake

+CHECK_STRUCT_HAS_MEMBER ("struct stat" st_mtim "sys/types.h;sys/stat.h"
+	HAVE_STRUCT_STAT_ST_MTIM LANGUAGE C)
+CHECK_STRUCT_HAS_MEMBER ("struct stat" st_mtimespec "sys/types.h;sys/stat.h"
+	HAVE_STRUCT_STAT_ST_MTIMESPEC LANGUAGE C)
+CHECK_STRUCT_HAS_MEMBER("struct stat" st_mtime_nsec sys/stat.h
+	HAVE_STRUCT_STAT_MTIME_NSEC LANGUAGE C)
+
+IF (HAVE_STRUCT_STAT_ST_MTIM)
+	CHECK_STRUCT_HAS_MEMBER("struct stat" st_mtim.tv_nsec sys/stat.h
+		HAVE_STRUCT_STAT_NSEC LANGUAGE C)
+ELSEIF (HAVE_STRUCT_STAT_ST_MTIMESPEC)
+	CHECK_STRUCT_HAS_MEMBER("struct stat" st_mtimespec.tv_nsec sys/stat.h
+		HAVE_STRUCT_STAT_NSEC LANGUAGE C)
+ELSE ()
+	SET( HAVE_STRUCT_STAT_NSEC ON )
+ENDIF()
+
+IF (HAVE_STRUCT_STAT_NSEC OR WIN32)
+	OPTION( USE_NSEC		"Care about sub-second file mtimes and ctimes"	ON  )
+ENDIF()