Windows build fails due to several treat-warning-as-errors

##Configure:

* Environment: cygwin version 3.1.7(0.340/5/3), 2020-08-22 17:48; windows version 10.0.19041.804; prefix "/cygdrive"; root "F:\cygwin64"
* Boot JDK: java version "15.0.2" 2021-01-19 Java(TM) SE Runtime Environment (build 15.0.2+7-27) Java HotSpot(TM) 64-Bit Server VM (build 15.0.2+7-27, mixed mode, sharing) (at /cygdrive/f/java/jdk-15.0.2)
* Toolchain: microsoft (Microsoft Visual Studio 2019)
* C Compiler: Version 19.28.29334 (at /cygdrive/c/progra~2/vsudio/2019/community/vc/tools/msvc/14.28.29333/bin/hostx86/x64/cl.exe)
* C++ Compiler: Version 19.28.29334 (at /cygdrive/c/progra~2/vsudio/2019/community/vc/tools/msvc/14.28.29333/bin/hostx86/x64/cl.exe)


## Failure log:
1. methodMatcher.cpp
=== Output from failing command(s) repeated here ===
* For target hotspot_variant-server_libjvm_objs_methodMatcher.obj:
methodMatcher.cpp
f:\openjdk16\src\hotspot\share\compiler\methodMatcher.cpp(269): error C2220: the following warning is treated as an error
f:\openjdk16\src\hotspot\share\compiler\methodMatcher.cpp(269): warning C4476: 'sscanf' : unknown type field character '&' in format specifier
f:\openjdk16\src\hotspot\share\compiler\methodMatcher.cpp(269): warning C4477: 'sscanf' : format string '%n' requires an argument of type 'int *', but variadic argument 1 has type 'char *'
f:\openjdk16\src\hotspot\share\compiler\methodMatcher.cpp(269): note: consider using '%hhn' in the format string
f:\openjdk16\src\hotspot\share\compiler\methodMatcher.cpp(269): warning C4474: 'sscanf' : too many arguments passed for format string
f:\openjdk16\src\hotspot\share\compiler\methodMatcher.cpp(269): note: placeholders and their parameters expect 1 variadic arguments, but 3 were provided
f:\openjdk16\src\hotspot\share\compiler\methodMatcher.cpp(319): warning C4778: 'sscanf' : unterminated format string '%1022[[);/\x01\x02\x03\x04\x05\x06\a\b\n\v\f\r\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f!\"#$%&'*+,-0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ\\^_`abcdefghijklmnopqrstuvwxyz{|}~\xe2\x82\xac\xe4\xba\x97\xe5\x84\x8e\xe5\x8e%n'
f:\openjdk16\src\hotspot\share\compiler\methodMatcher.cpp(319): warning C4474: 'sscanf' : too many arguments passed for format string
f:\openjdk16\src\hotspot\share\compiler\methodMatcher.cpp(319): note: placeholders and their parameters expect 0 variadic arguments, but 2 were provided
   ... (rest of output omitted)

* All command lines available in /cygdrive/f/openjdk16/build/windows-x86_64-server-release/make-support/failure-logs.
=== End of repeated output ===

2. vm_version_x86.cpp
=== Output from failing command(s) repeated here ===
* For target hotspot_variant-server_libjvm_objs_vm_version_x86.obj:
vm_version_x86.cpp
f:\openjdk16\src\hotspot\cpu\x86\vm_version_x86.cpp(1655): error C2220: the following warning is treated as an error
f:\openjdk16\src\hotspot\cpu\x86\vm_version_x86.cpp(1655): warning C4819: The file contains a character that cannot be represented in the current code page (936). Save the file in Unicode format to prevent data loss
   ... (rest of output omitted)

* All command lines available in /cygdrive/f/openjdk16/build/windows-x86_64-server-release/make-support/failure-logs.
=== End of repeated output ===