normalize flags and rustc version in ICE repro

Author: RalfJung

src/test/ui/pattern/const-pat-ice.rs

@@ -1,5 +1,7 @@
 // failure-status: 101
 // rustc-env:RUST_BACKTRACE=0
+// normalize-stderr-test "note: rustc 1.* running on .*" -> "note: rustc VERSION running on TARGET"
+// normalize-stderr-test "note: compiler flags: .*" -> "note: compiler flags: FLAGS"
 
 // This is a repro test for an ICE in our pattern handling of constants.
 

src/test/ui/pattern/const-pat-ice.stderr

@@ -7,7 +7,7 @@ note: the compiler unexpectedly panicked. this is a bug.
 
 note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
 
-note: rustc 1.35.0-dev running on x86_64-unknown-linux-gnu
+note: rustc VERSION running on TARGET
 
-note: compiler flags: -Z threads=1 -Z ui-testing -Z unstable-options -C prefer-dynamic -C rpath
+note: compiler flags: FLAGS