vmbase: Rename configure_global_allocator_size

Test: -
Change-Id: Iae7130f235893a4ac8a55f8f5d2295eea22193ef
diff --git a/vmbase/src/heap.rs b/vmbase/src/heap.rs
index 08240b9..b00ca6f 100644
--- a/vmbase/src/heap.rs
+++ b/vmbase/src/heap.rs
@@ -29,7 +29,7 @@
 
 /// Configures the size of the global allocator.
 #[macro_export]
-macro_rules! configure_global_allocator_size {
+macro_rules! configure_heap {
     ($len:expr) => {
         static mut __HEAP_ARRAY: [u8; $len] = [0; $len];
         #[export_name = "HEAP"]
@@ -39,7 +39,7 @@
 }
 
 extern "Rust" {
-    /// Slice used by the global allocator, configured using configure_global_allocator_size!().
+    /// Slice used by the global allocator, configured using configure_heap!().
     static mut HEAP: &'static mut [u8];
 }