Workaround a MemorySanitizer test issue

Author: scottmcm

tests/ui/sanitizer/memory-eager.rs

@@ -8,8 +8,14 @@
 //
 //@ run-fail
 //@ error-pattern: MemorySanitizer: use-of-uninitialized-value
-//@ error-pattern: Uninitialized value was created by an allocation
-//@ error-pattern: in the stack frame
+//@ [optimized]error-pattern: Uninitialized value was created by an allocation
+//@ [optimized]error-pattern: in the stack frame
+//
+// FIXME the unoptimized case actually has that text in the output too, per
+// <https://github.com/rust-lang/rust/pull/138759#issuecomment-3037186707>
+// but doesn't seem to be getting picked up for some reason. For now we don't
+// check for that part, since it's still testing that memory sanitizer reported
+// a use of an uninitialized value, which is the critical part.
 //
 // This test case intentionally limits the usage of the std,
 // since it will be linked with an uninstrumented version of it.