git_libgit2_version: return an int

Stop returning a void for functions, future-proofing them to allow them
to fail.

include/git2/common.h

@@ -117,8 +117,9 @@ GIT_BEGIN_DECL
  * @param major Store the major version number
  * @param minor Store the minor version number
  * @param rev Store the revision (patch) number
+ * @return 0 on success or an error code on failure
  */
-GIT_EXTERN(void) git_libgit2_version(int *major, int *minor, int *rev);
+GIT_EXTERN(int) git_libgit2_version(int *major, int *minor, int *rev);
 
 /**
  * Combinations of these values describe the features with which libgit2

src/settings.c

@@ -29,11 +29,13 @@
 #include "streams/openssl.h"
 #include "streams/mbedtls.h"
 
-void git_libgit2_version(int *major, int *minor, int *rev)
+int git_libgit2_version(int *major, int *minor, int *rev)
 {
 	*major = LIBGIT2_VER_MAJOR;
 	*minor = LIBGIT2_VER_MINOR;
 	*rev = LIBGIT2_VER_REVISION;
+
+	return 0;
 }
 
 int git_libgit2_features(void)