rm the unused calloc wrapper from memory_region

it doesn't actually call calloc, so it's fairly pointless

src/rt/memory_region.cpp

@@ -121,8 +121,10 @@ memory_region::realloc(void *mem, size_t orig_size) {
 }
 
 void *
-memory_region::malloc(size_t size, const char *tag, bool zero) {
+memory_region::malloc(size_t size, const char *tag) {
+#   if RUSTRT_TRACK_ALLOCATIONS >= 1
     size_t old_size = size;
+#   endif
     size += HEADER_SIZE;
     alloc_header *mem = (alloc_header *)::malloc(size);
     if (mem == NULL) {
@@ -143,18 +145,9 @@ memory_region::malloc(size_t size, const char *tag, bool zero) {
     void *data = get_data(mem);
     claim_alloc(data);
 
-    if(zero) {
-        memset(data, 0, old_size);
-    }
-
     return data;
 }
 
-void *
-memory_region::calloc(size_t size, const char *tag) {
-    return malloc(size, tag, true);
-}
-
 memory_region::~memory_region() {
     if (_synchronized) { _lock.lock(); }
     if (_live_allocations == 0 && !_detailed_leaks) {

src/rt/memory_region.h

@@ -77,8 +77,7 @@ private:
 public:
     memory_region(rust_env *env, bool synchronized);
     memory_region(memory_region *parent);
-    void *malloc(size_t size, const char *tag, bool zero = true);
-    void *calloc(size_t size, const char *tag);
+    void *malloc(size_t size, const char *tag);
     void *realloc(void *mem, size_t size);
     void free(void *mem);
     ~memory_region();

src/rt/rust_stack.cpp

@@ -58,7 +58,7 @@ check_stack_canary(stk_seg *stk) {
 stk_seg *
 create_stack(memory_region *region, size_t sz) {
     size_t total_sz = sizeof(stk_seg) + sz;
-    stk_seg *stk = (stk_seg *)region->malloc(total_sz, "stack", false);
+    stk_seg *stk = (stk_seg *)region->malloc(total_sz, "stack");
     memset(stk, 0, sizeof(stk_seg));
     stk->end = (uintptr_t) &stk->data[sz];
     add_stack_canary(stk);

src/rt/rust_task.cpp

@@ -450,11 +450,6 @@ rust_task::backtrace() {
 #endif
 }
 
-void *
-rust_task::calloc(size_t size, const char *tag) {
-    return local_region.calloc(size, tag);
-}
-
 size_t
 rust_task::get_next_stack_size(size_t min, size_t current, size_t requested) {
     LOG(this, mem, "calculating new stack size for 0x%" PRIxPTR, this);