Add explcit `--error-format` options to tests of print-fuel to sidestep...

Add explcit `--error-format` options to tests of print-fuel to sidestep compiletests presumption of JSON.

As a driveby, rename the stdout files to stderr, which should have been part of the earlier commit.

src/test/run-pass/optimization-fuel-0.rs

@@ -12,7 +12,8 @@
 
 use std::mem::size_of;
 
-// compile-flags: -Z fuel=foo=0
+// (#55495: The --error-format is to sidestep an issue in our test harness)
+// compile-flags: --error-format human -Z fuel=foo=0
 
 struct S1(u8, u16, u8);
 struct S2(u8, u16, u8);

src/test/run-pass/optimization-fuel-1.rs

@@ -12,7 +12,8 @@
 
 use std::mem::size_of;
 
-// compile-flags: -Z fuel=foo=1
+// (#55495: The --error-format is to sidestep an issue in our test harness)
+// compile-flags: --error-format human -Z fuel=foo=1
 
 struct S1(u8, u16, u8);
 struct S2(u8, u16, u8);

src/test/ui/print-fuel/print-fuel.rs

@@ -11,7 +11,8 @@
 #![crate_name="foo"]
 #![allow(dead_code)]
 
-// compile-flags: -Z print-fuel=foo
+// (#55495: The --error-format is to sidestep an issue in our test harness)
+// compile-flags: --error-format human -Z print-fuel=foo
 // compile-pass
 
 struct S1(u8, u16, u8);