Fix wrong variable reference.

Bug: 125891203

Test: Verify that setting the program property to "" doesn't trigger
Test: heapprofd.
Change-Id: Id27cbb92c7a120d02151e29be993f369230c2de8
diff --git a/libc/bionic/malloc_heapprofd.cpp b/libc/bionic/malloc_heapprofd.cpp
index c492bac..5129cd7 100644
--- a/libc/bionic/malloc_heapprofd.cpp
+++ b/libc/bionic/malloc_heapprofd.cpp
@@ -202,7 +202,7 @@
   if (__system_property_get(program_property, property_value) == 0) {
     return false;
   }
-  return program_property[0] != '\0';
+  return property_value[0] != '\0';
 }
 
 void HeapprofdInstallSignalHandler() {