Fix build issues on MSVC

MSVC doesn't support C99 variable sized automatic arrays, so use malloc
instead. It also requires at least one value for struct initializers.

src/disp/program.c

@@ -1989,7 +1989,8 @@ static void emit_args_ops(MVMThreadContext *tc, MVMCallStackDispatchRecord *reco
             Action action;
             MVMuint32 index;
         } ArgProduction;
-        ArgProduction arg_prod[num_to_produce];
+        ArgProduction *arg_prod = MVM_malloc(num_to_produce * sizeof(ArgProduction));
+
         for (i = 0; i < num_to_produce; i++) {
             /* Work out the source of this arg in the capture. For the rationale
              * for this algorithm, see MVM_disp_program_record_track_arg. */
@@ -2060,6 +2061,8 @@ static void emit_args_ops(MVMThreadContext *tc, MVMCallStackDispatchRecord *reco
             MVM_VECTOR_PUSH(cs->ops, op);
         }
 
+        MVM_free(arg_prod);
+
         /* Finally, the instruction to copy what we can from the args tail. */
         MVMDispProgramOp op;
         op.code = MVMDispOpcodeCopyArgsTail;

src/disp/syscall.c

@@ -328,9 +328,9 @@ static MVMDispSysCall dispatcher_get_resume_init_args = {
     .implementation = dispatcher_get_resume_init_args_impl,
     .min_args = 0,
     .max_args = 0,
-    .expected_kinds = { },
-    .expected_reprs = { },
-    .expected_concrete = { },
+    .expected_kinds = {0},
+    .expected_reprs = {0},
+    .expected_concrete = {0},
 };
 
 /* dispatcher-set-resume-state */
@@ -381,9 +381,9 @@ static MVMDispSysCall dispatcher_get_resume_state = {
     .implementation = dispatcher_get_resume_state_impl,
     .min_args = 0,
     .max_args = 0,
-    .expected_kinds = { },
-    .expected_reprs = { },
-    .expected_concrete = { },
+    .expected_kinds = {0},
+    .expected_reprs = {0},
+    .expected_concrete = {0}
 };
 
 /* dispatcher-track-resume-state */
@@ -398,9 +398,9 @@ static MVMDispSysCall dispatcher_track_resume_state = {
     .implementation = dispatcher_track_resume_state_impl,
     .min_args = 0,
     .max_args = 0,
-    .expected_kinds = { },
-    .expected_reprs = { },
-    .expected_concrete = { },
+    .expected_kinds = {0},
+    .expected_reprs = {0},
+    .expected_concrete = {0}
 };
 
 /* dispatcher-next-resumption */
@@ -415,9 +415,9 @@ static MVMDispSysCall dispatcher_next_resumption = {
     .implementation = dispatcher_next_resumption_impl,
     .min_args = 0,
     .max_args = 0,
-    .expected_kinds = { },
-    .expected_reprs = { },
-    .expected_concrete = { },
+    .expected_kinds = {0},
+    .expected_reprs = {0},
+    .expected_concrete = {0}
 };
 
 /* dispatcher-resume-on-bind-failure */
@@ -467,9 +467,9 @@ static MVMDispSysCall dispatcher_inline_cache_size = {
     .implementation = dispatcher_inline_cache_size_impl,
     .min_args = 0,
     .max_args = 0,
-    .expected_kinds = { },
-    .expected_reprs = { },
-    .expected_concrete = { },
+    .expected_kinds = {0},
+    .expected_reprs = {0},
+    .expected_concrete = {0}
 };
 
 /* capture-is-literal-arg */
@@ -945,9 +945,9 @@ static MVMDispSysCall bind_will_resume_on_failure = {
     .implementation = bind_will_resume_on_failure_impl,
     .min_args = 0,
     .max_args = 0,
-    .expected_kinds = { },
-    .expected_reprs = { },
-    .expected_concrete = { },
+    .expected_kinds = {0},
+    .expected_reprs = {0},
+    .expected_concrete = {0},
 };
 
 /* Add all of the syscalls into the hash. */