chore: avoid setting GGML_MAX_NAME when building against external ggml (#751)

An external ggml will most likely have been built with the default
GGML_MAX_NAME value (64), which would be inconsistent with the value
set by our build (128). That would be an ODR violation, and it could
easily cause memory corruption issues due to the different
sizeof(struct ggml_tensor) values.

For now, when linking against an external ggml, we demand it has been
patched with a bigger GGML_MAX_NAME, since we can't check against a
value defined only at build time.

Author: wbruna

CMakeLists.txt

@@ -119,8 +119,10 @@ endif()
 
 set(CMAKE_POLICY_DEFAULT_CMP0077 NEW)
 
-# see https://github.com/ggerganov/ggml/pull/682
-add_definitions(-DGGML_MAX_NAME=128)
+if (NOT SD_USE_SYSTEM_GGML)
+    # see https://github.com/ggerganov/ggml/pull/682
+    add_definitions(-DGGML_MAX_NAME=128)
+endif()
 
 # deps
 # Only add ggml if it hasn't been added yet

ggml_extend.hpp

@@ -56,6 +56,8 @@
 #define __STATIC_INLINE__ static inline
 #endif
 
+static_assert(GGML_MAX_NAME >= 128, "GGML_MAX_NAME must be at least 128");
+
 // n-mode trensor-matrix product
 // example: 2-mode product
 // A: [ne03, k, ne01, ne00]