[bolt] Clean up lit site cfg files a bit

[thakis]

Summary

• Stop setting config.python_executable in Unit/lit.site.cfg.py.in. All other projects only set this in the main lit config, not in the one for unit tests. (Unit tests don't spawn Python.)
• Set config.python_executable to Python3_EXECUTABLE in main lit.site.cfg.py.in instead of PYTHON_EXECUTABLE. All other files did this in c4c3883b00.
• Stop setting enable_abi_breaking_checks, enable_backtrace, enable_shared. Nothing in bolt's tests (or in lit) reads them.

[rafauler]

Thanks!

bolt/test/Unit/lit.site.cfg.py.in

 @LIT_SITE_CFG_IN_HEADER@
 
 config.llvm_src_root = "@LLVM_SOURCE_DIR@"
 config.llvm_obj_root = "@LLVM_BINARY_DIR@"
 config.llvm_tools_dir = lit_config.substitute("@LLVM_TOOLS_DIR@")
 config.llvm_libs_dir = lit_config.substitute("@LLVM_LIBS_DIR@")
 config.llvm_build_mode = lit_config.substitute("@LLVM_BUILD_MODE@")
 config.lit_tools_dir = "@LLVM_LIT_TOOLS_DIR@"
 config.bolt_obj_root = "@BOLT_BINARY_DIR@"
 config.bolt_src_root = "@BOLT_SOURCE_DIR@"
 config.target_triple = "@LLVM_TARGET_TRIPLE@"
-config.python_executable = "@Python3_EXECUTABLE@"
 
 import lit.llvm
 lit.llvm.initialize(lit_config, config)
 
 # Let the main config do the real work.
 lit_config.load_config(config, "@BOLT_SOURCE_DIR@/test/Unit/lit.cfg.py")

bolt/test/lit.site.cfg.py.in

 @LIT_SITE_CFG_IN_HEADER@
 
 import sys
 
 config.llvm_src_root = "@LLVM_SOURCE_DIR@"
 config.llvm_obj_root = "@LLVM_BINARY_DIR@"
 config.bolt_obj_root = "@BOLT_BINARY_DIR@"
 config.bolt_enable_runtime = @BOLT_ENABLE_RUNTIME@
 config.llvm_tools_dir = lit_config.substitute("@LLVM_TOOLS_DIR@")
 config.llvm_libs_dir = lit_config.substitute("@LLVM_LIBS_DIR@")
 config.llvm_shlib_dir = lit_config.substitute("@SHLIBDIR@")
 config.llvm_plugin_ext = "@LLVM_PLUGIN_EXT@"
 config.lit_tools_dir = "@LLVM_LIT_TOOLS_DIR@"
 config.host_triple = "@LLVM_HOST_TRIPLE@"
 config.target_triple = "@LLVM_TARGET_TRIPLE@"
 config.llvm_use_sanitizer = "@LLVM_USE_SANITIZER@"
-config.enable_shared = @ENABLE_SHARED@
-config.enable_backtrace = @ENABLE_BACKTRACES@
 config.host_arch = "@HOST_ARCH@"
-config.enable_abi_breaking_checks = "@LLVM_ENABLE_ABI_BREAKING_CHECKS@"
-config.python_executable = "@PYTHON_EXECUTABLE@"
+config.python_executable = "@Python3_EXECUTABLE@"
 config.bolt_clang = "@BOLT_CLANG_EXE@"
 config.bolt_lld = "@BOLT_LLD_EXE@"
 config.targets_to_build = "@TARGETS_TO_BUILD@"
 config.gnu_ld = "@GNU_LD_EXECUTABLE@"
 
 import lit.llvm
 lit.llvm.initialize(lit_config, config)
 
 # Let the main config do the real work.
 lit_config.load_config(config, "@BOLT_SOURCE_DIR@/test/lit.cfg.py")