[cmake][Fuchsia] Default to all crash diagnostics

[abrachet]

Summary

This makes Fuchsia's clang reproduce linker crashes in addition to
compiler crashes by default.

Passing -fcrash-diagnostics=compiler will use the old behavior.

clang/cmake/caches/Fuchsia-stage2.cmake

 set(CLANG_DEFAULT_CXX_STDLIB libc++ CACHE STRING "")
 set(CLANG_DEFAULT_LINKER lld CACHE STRING "")
 set(CLANG_DEFAULT_OBJCOPY llvm-objcopy CACHE STRING "")
 set(CLANG_DEFAULT_RTLIB compiler-rt CACHE STRING "")
 set(CLANG_DEFAULT_UNWINDLIB libunwind CACHE STRING "")
 set(CLANG_ENABLE_ARCMT OFF CACHE BOOL "")
 set(CLANG_ENABLE_STATIC_ANALYZER ON CACHE BOOL "")
 set(CLANG_PLUGIN_SUPPORT OFF CACHE BOOL "")
+set(CLANG_DEFAULT_CRASH_DIAG_LEVEL CLANG_CRASH_DIAG_ALL CACHE STRING "")
 
 set(ENABLE_LINKER_BUILD_ID ON CACHE BOOL "")
 set(ENABLE_X86_RELAX_RELOCATIONS ON CACHE BOOL "")
 
 set(CMAKE_BUILD_TYPE Release CACHE STRING "")
 if (APPLE)
   set(CMAKE_OSX_DEPLOYMENT_TARGET "10.13" CACHE STRING "")
 elseif(WIN32)

clang/cmake/caches/Fuchsia.cmake

 set(CLANG_DEFAULT_CXX_STDLIB libc++ CACHE STRING "")
 set(CLANG_DEFAULT_LINKER lld CACHE STRING "")
 set(CLANG_DEFAULT_OBJCOPY llvm-objcopy CACHE STRING "")
 set(CLANG_DEFAULT_RTLIB compiler-rt CACHE STRING "")
 set(CLANG_DEFAULT_UNWINDLIB libunwind CACHE STRING "")
 set(CLANG_ENABLE_ARCMT OFF CACHE BOOL "")
 set(CLANG_ENABLE_STATIC_ANALYZER OFF CACHE BOOL "")
 set(CLANG_PLUGIN_SUPPORT OFF CACHE BOOL "")
+set(CLANG_DEFAULT_CRASH_DIAG_LEVEL CLANG_CRASH_DIAG_ALL CACHE STRING "")
 
 set(ENABLE_LINKER_BUILD_ID ON CACHE BOOL "")
 set(ENABLE_X86_RELAX_RELOCATIONS ON CACHE BOOL "")
 
 set(LLVM_ENABLE_ASSERTIONS ON CACHE BOOL "")
 set(LLVM_ENABLE_BACKTRACES ON CACHE BOOL "")
 set(CMAKE_BUILD_TYPE Release CACHE STRING "")
 if(APPLE)