Remove mention of "compiler-rt" from COPYRIGHT file

The compiler-rt dependency was removed in
7e6c9f3 in favor of a vendored
dependency on rust-lang/compiler-builtins (dual UIUC and MIT licensed).
That vendored dependency was converted to a regular Cargo dependency in
4c21a3b.

Author: wesleywiser

COPYRIGHT

@@ -76,87 +76,6 @@ their own copyright notices and license terms:
   BSD-compatible licenses. See src/llvm-project/llvm/LICENSE.TXT
   for details.
 
-* compiler-rt, in src/compiler-rt is dual licensed under
-  LLVM's license and MIT:
-
-    Copyright (c) 2009-2014 by the contributors listed in
-    CREDITS.TXT
-
-    All rights reserved.
-
-    Developed by:
-
-        LLVM Team
-
-        University of Illinois at Urbana-Champaign
-
-        http://llvm.org
-
-    Permission is hereby granted, free of charge, to any
-    person obtaining a copy of this software and associated
-    documentation files (the "Software"), to deal with the
-    Software without restriction, including without
-    limitation the rights to use, copy, modify, merge,
-    publish, distribute, sublicense, and/or sell copies of
-    the Software, and to permit persons to whom the Software
-    is furnished to do so, subject to the following
-    conditions:
-
-        * Redistributions of source code must retain the
-          above copyright notice, this list of conditions
-          and the following disclaimers.
-
-        * Redistributions in binary form must reproduce the
-          above copyright notice, this list of conditions
-          and the following disclaimers in the documentation
-          and/or other materials provided with the
-          distribution.
-
-        * Neither the names of the LLVM Team, University of
-          Illinois at Urbana-Champaign, nor the names of its
-          contributors may be used to endorse or promote
-          products derived from this Software without
-          specific prior written permission.
-
-    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
-    ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
-    TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
-    PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT
-    SHALL THE CONTRIBUTORS OR COPYRIGHT HOLDERS BE LIABLE
-    FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
-    ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT
-    OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
-    OTHER DEALINGS WITH THE SOFTWARE.
-
-    ========================================================
-
-    Copyright (c) 2009-2014 by the contributors listed in
-    CREDITS.TXT
-
-    Permission is hereby granted, free of charge, to any
-    person obtaining a copy of this software and associated
-    documentation files (the "Software"), to deal in the
-    Software without restriction, including without
-    limitation the rights to use, copy, modify, merge,
-    publish, distribute, sublicense, and/or sell copies of
-    the Software, and to permit persons to whom the Software
-    is furnished to do so, subject to the following
-    conditions:
-
-    The above copyright notice and this permission notice
-    shall be included in all copies or substantial portions
-    of the Software.
-
-    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
-    ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
-    TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
-    PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
-    SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
-    CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
-    OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
-    IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
-    DEALINGS IN THE SOFTWARE.
-
 * Portions of the FFI code for interacting with the native ABI
   is derived from the Clay programming language, which carries
   the following license.