Bug 1840008 - Undo bug 1632776. r=firefox-build-system-reviewers,andi

The bug it worked around
(rust-lang/rust#61002) was fixed in rustc
1.55, and we currently require 1.66.

Differential Revision: https://phabricator.services.mozilla.com/D181843

UltraBlame original commit: 70bf3adb2de59cdd39165ebe10cbd76dcc70c6da

Author: marco-c

config/makefiles/rust.mk

@@ -1934,120 +1934,11 @@ ifdef
 MOZ_PGO_RUST
 ifdef
 MOZ_PROFILE_GENERATE
-#
-Our
-top
--
-level
-Cargo
-.
-toml
-sets
-panic
-to
-abort
-so
-we
-technically
-don
-'
-t
-need
--
-C
-panic
-=
-abort
-#
-but
-the
-autocfg
-crate
-takes
-RUSTFLAGS
-verbatim
-and
-runs
-its
-compiler
-tests
-without
-#
--
-C
-panic
-=
-abort
-(
-because
-it
-doesn
-'
-t
-know
-it
-'
-s
-what
-cargo
-uses
-)
-which
-fail
-on
-Windows
-#
-because
--
-C
-panic
-=
-unwind
-(
-the
-compiler
-default
-)
-is
-not
-compatible
-with
--
-C
-profile
--
-generate
-#
-(
-https
-:
-/
-/
-github
-.
-com
-/
-rust
--
-lang
-/
-rust
-/
-issues
-/
-61002
-)
-.
 rust_pgo_flags
 :
 =
 -
 C
-panic
-=
-abort
--
-C
 profile
 -
 generate