[libfuzzer] Re-enable libFuzzer tests in "check-all"

[vitalybuka]

Could please you put into description short explanation or submitted patch to explain why we can re-enable this now?

[kubamracek]

I thought that libFuzzer is stable enough these days to be tested by default on supported platforms, but @george.karpenkov just explained to me that that's probably not the case as there are tests that tend to be flaky and cause timeouts (worst type of failures). Are there more reasons why we have EXCLUDE_FROM_ALL?

[kubamracek]

Apparently, someone else landed the exact same patch recently. Abandoning.

test/fuzzer/CMakeLists.txt

 set(LIBFUZZER_TEST_DEPS ${SANITIZER_COMMON_LIT_TEST_DEPS})
 if (NOT COMPILER_RT_STANDALONE_BUILD)
   list(APPEND LIBFUZZER_TEST_DEPS fuzzer asan ubsan)
 endif()
 
 if(COMPILER_RT_INCLUDE_TESTS)
   list(APPEND LIBFUZZER_TEST_DEPS FuzzerUnitTests)
 endif()
 
-set(EXCLUDE_FROM_ALL ON)
-
 add_custom_target(check-fuzzer)
 
 if(COMPILER_RT_INCLUDE_TESTS)
   # libFuzzer unit tests.
   configure_lit_site_cfg(
     ${CMAKE_CURRENT_SOURCE_DIR}/unit/lit.site.cfg.in
     ${CMAKE_CURRENT_BINARY_DIR}/unit/lit.site.cfg)
   add_lit_testsuite(check-fuzzer-unit "Running Fuzzer unit tests"