Make normalization regex less exact

Author: ChrisDenton

src/tools/miri/tests/fail/alloc/global_system_mixup.rs

@@ -4,7 +4,7 @@
 
 //@normalize-stderr-test: "using [A-Za-z]+ heap deallocation operation" -> "using PLATFORM heap deallocation operation"
 //@normalize-stderr-test: "\| +\^+" -> "| ^"
-//@normalize-stderr-test: "libc::free\([^()]*\)|unsafe \{ HeapFree\([^()]*\) \};" -> "FREE();"
+//@normalize-stderr-test: "libc::free\([^()]*\)|unsafe \{ HeapFree\([^}]*\};" -> "FREE();"
 
 #![feature(allocator_api, slice_ptr_get)]