baselibc: Add option to enable extra debugging for malloc/free

Author: andrzej-kaczmarek

libc/baselibc/pkg.yml

@@ -34,6 +34,9 @@ pkg.init.BASELIBC_THREAD_SAFE_HEAP_ALLOCATION:
 pkg.cflags:
     - -fno-builtin-malloc
 
+pkg.cflags.BASELIBC_DEBUG_MALLOC:
+    - -DDEBUG_MALLOC
+
 pkg.lflags:
     - -specs=nosys.specs:
     - -umain

libc/baselibc/syscfg.yml

@@ -41,3 +41,9 @@ syscfg.defs:
         description: >
             Set to 1 if project requires malloc/calloc/free to be thread safe.
         value: 0
+
+    BASELIBC_DEBUG_MALLOC:
+        description: >
+            Set to 1 to enable extra debugging for malloc/free calls.
+            This will e.g. assert on double-free.
+        value: 0