ggml : make more compatible with c99 (#262)

ggml.c

@@ -14,9 +14,10 @@
 #include <stdint.h>
 #include <stdio.h>
 
-// if C99 - static_assert is nop
+// if C99 - static_assert is noop
+// ref: https://stackoverflow.com/a/53923785/4039976
 #ifndef static_assert
-#define static_assert(cond, msg)
+#define static_assert(cond, msg) struct global_scope_noop_trick
 #endif
 
 #if defined _MSC_VER || defined(__MINGW32__)

ggml.h

@@ -681,7 +681,6 @@ struct ggml_opt_params {
     bool print_forward_graph;
     bool print_backward_graph;
 
-    union {
     // ADAM parameters
     struct {
         int n_iter;
@@ -709,7 +708,6 @@ struct ggml_opt_params {
         enum ggml_linesearch linesearch;
     } lbfgs;
 };
-};
 
 struct ggml_opt_params ggml_opt_default_params(enum ggml_opt_type type);