[libFuzzer] Use separate test directory for each config

[jdenny]

Summary

Previously, check-all failed many tests for me. It was running the
X86_64DefaultLinuxConfig, X86_64LibcxxLinuxConfig, and
X86_64StaticLibcxxLinuxConfig configs out of
llvm-build/projects/compiler-rt/test/fuzzer. Now, it runs them out of
separate subdirectories there, and most tests pass.

[morehouse]

The other test configs don't define config.test_exec_root at all. Do we need it?

[george.karpenkov]

@morehouse unit tests for other sanitizers do though.
I'm a bit confused on what exactly is happening here, and why tests pass on other platforms

[jdenny]

In D49249#1161704, @morehouse wrote:

The other test configs don't define config.test_exec_root at all. Do we need it?

It seems we don't. I removed it, and the tests pass. I'll upload a new patch.

In D49249#1165477, @george.karpenkov wrote:

@morehouse unit tests for other sanitizers do though.
I'm a bit confused on what exactly is happening here,

The same tests were being run for different configs, which thus shared output files. By setting different directories for different configs, they no longer share output files.

and why tests pass on other platforms

I haven't explored other platforms. Do they ever support multiple conflicting configs (like X86_64DefaultLinuxConfig and X86_64LibcxxLinuxConfig)?

[jdenny]

Removed config.test_exec_root, which is unique to each config by default.

[morehouse]

Please watch the bots after landing this.

compiler-rt/trunk/test/fuzzer/lit.site.cfg.in

 @LIT_SITE_CFG_IN_HEADER@
 
-config.test_exec_root = "@CMAKE_CURRENT_BINARY_DIR@"
-
 config.cpp_compiler = "@LIBFUZZER_TEST_COMPILER@"
 config.target_flags = "@LIBFUZZER_TEST_FLAGS@"
 config.c_compiler = "@LIBFUZZER_TEST_COMPILER@"
 config.stdlib = "@LIBFUZZER_TEST_STDLIB@"
 config.apple_platform = "@LIBFUZZER_TEST_APPLE_PLATFORM@"
 config.name_suffix = "@LIBFUZZER_TEST_CONFIG_SUFFIX@"
 
 config.osx_sysroot_flag = "@OSX_SYSROOT_FLAG@"