[scudo] Enable more warnings for standalone build

[ddcc]

ping

[lei]

Please note that this patch broke any bots that build this project with -Werror (example: https://lab.llvm.org/buildbot/#/builders/19/builds/14037). As a result, I have reverted it since there has been no fix within a reasonable time.
May I advise ensuring that a project is clean wrt. to the additional warnings when turning on extra warnings as there are bound to be some builds that use -Werror. Also, new warnings are almost always disruptive changes as there are many different build configurations that may be affected in unforeseen ways. If you have such a disruptive change ready to commit, it is advisable to wait until Monday to commit it rather than committing it on a Friday evening as most people are disconnecting.

[ddcc]

Sorry, I tested it when I opened the revision but forgot to account for changes since then.

[ddcc]

Add fix for unused variable

[ddcc]

Ran a local build and this should be the only fix needed, will see what the CI results say

compiler-rt/lib/scudo/standalone/CMakeLists.txt

 add_compiler_rt_component(scudo_standalone)
 
 include_directories(../.. include)
 
 set(SCUDO_CFLAGS)
 
 list(APPEND SCUDO_CFLAGS
   -Werror=conversion
   -Wall
+  -Wextra
+  -pedantic
   -g
   -nostdinc++)
 
 # Remove -stdlib= which is unused when passing -nostdinc++.
 string(REGEX REPLACE "-stdlib=[a-zA-Z+]*" "" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
 
 append_list_if(COMPILER_RT_HAS_FVISIBILITY_HIDDEN_FLAG -fvisibility=hidden SCUDO_CFLAGS)