Add folly::sizedFree

Summary:
Add folly::sizedFree

(Note: this ignores all push blocking failures!)

Reviewed By: ot

Differential Revision: D19944311

fbshipit-source-id: b5b1a648a180662fe838237c3c3b153e42fe0617

folly/memory/Malloc.h

@@ -180,6 +180,14 @@ inline void* checkedRealloc(void* ptr, size_t size) {
   return p;
 }
 
+inline void sizedFree(void* ptr, size_t size) {
+  if (usingJEMalloc()) {
+    sdallocx(ptr, size, 0);
+  } else {
+    free(ptr);
+  }
+}
+
 /**
  * This function tries to reallocate a buffer of which only the first
  * currentSize bytes are used. The problem with using realloc is that