ggml : add version function to get lib version (ggml/1286)

* ggml : add version function to get lib version

This commit adds a function `ggml_version()` to the ggml library that
returns the version of the library as a string.

The motivation for this is that it can be useful to be able to
programmatically check the version of the ggml library being used.

Usage:
```c
printf("GGML version: %s\n", ggml_version());
```
Output:
```console
GGML version: 0.0.2219
```

* ggml : add ggml_commit()

---------

Co-authored-by: Georgi Gerganov <ggerganov@gmail.com>

ggml/src/ggml.c

@@ -473,6 +473,14 @@ bool ggml_guid_matches(ggml_guid_t guid_a, ggml_guid_t guid_b) {
     return memcmp(guid_a, guid_b, sizeof(ggml_guid)) == 0;
 }
 
+const char * ggml_version(void) {
+    return GGML_VERSION;
+}
+
+const char * ggml_commit(void) {
+    return GGML_COMMIT;
+}
+
 //
 // timing
 //