mtmd: fit_params now take into account mmproj (#21489)

* mtmd: fit_params now take into account mmproj

* rename alloc_compute_meta to reserve_compute_meta

* rm unused functions

* add ggml_backend_dev_t support

* add debug log

tools/mtmd/mtmd.h

@@ -9,6 +9,7 @@
 #include <stdbool.h>
 
 #ifdef __cplusplus
+#include <map>
 #include <string>
 #include <vector>
 #include <cinttypes>
@@ -261,6 +262,14 @@ MTMD_API mtmd_input_chunks * mtmd_test_create_input_chunks(void);
 } // extern "C"
 #endif
 
+// Get memory usage of the current model in bytes, per backend device
+// Note: this is an unstable API, used internally by fit_params; it WILL be removed or changed without deprecation
+#ifdef __cplusplus
+MTMD_API std::map<ggml_backend_dev_t, size_t> mtmd_get_memory_usage(
+    const char * mmproj_fname,
+    struct mtmd_context_params ctx_params);
+#endif
+
 //
 // C++ wrappers
 //