[lldb][NFC] Fix some invalid escapes sequences in Python strings

[teemperor]

Summary

I recently had to run the test suite with a debug Python which got started warning about some invalid
escape sequences in LLDB's Python code. They all attempt to add a backslash by doing a single
backslash instead of a double backslash in a normal string. This seems to work fine for now, but
Python says this behaviour is deprecated, so this patch turns all those strings into raw strings (where
a single backslash is actually a single backslash)

llvm/utils/lit/lit/TestRunner.py

substitutions.extend([
             ('%/p', sourcedir.replace('\\', '/')),
             ('%/t', tmpBase.replace('\\', '/') + '.tmp'),
             ('%/T', tmpDir.replace('\\', '/')),
             ])
 
     # "%{/[STpst]:regex_replacement}" should be normalized like "%/[STpst]" but we're
     # also in a regex replacement context of a s@@@ regex.
     def regex_escape(s):
-        s = s.replace('@', '\@')
-        s = s.replace('&', '\&')
+        s = s.replace('@', r'\@')
+        s = s.replace('&', r'\&')
         return s
     substitutions.extend([
             ('%{/s:regex_replacement}',
              regex_escape(sourcepath.replace('\\', '/'))),
             ('%{/S:regex_replacement}',
              regex_escape(sourcedir.replace('\\', '/'))),
             ('%{/p:regex_replacement}',
              regex_escape(sourcedir.replace('\\', '/'))),

llvm/utils/lit/lit/llvm/config.py

def use_clang(self, additional_tool_dirs=[], additional_flags=[], required=True):
         else:
             self.config.substitutions.append(
                 ('%target_itanium_abi_host_triple', ''))
 
         # FIXME: Find nicer way to prohibit this.
         self.config.substitutions.append(
             (' clang ', """\"*** Do not use 'clang' in tests, use '%clang'. ***\""""))
         self.config.substitutions.append(
-            (' clang\+\+ ', """\"*** Do not use 'clang++' in tests, use '%clangxx'. ***\""""))
+            (r' clang\+\+ ', """\"*** Do not use 'clang++' in tests, use '%clangxx'. ***\""""))
         self.config.substitutions.append(
             (' clang-cc ',
              """\"*** Do not use 'clang-cc' in tests, use '%clang_cc1'. ***\""""))
         self.config.substitutions.append(
             (' clang-cl ',
              """\"*** Do not use 'clang-cl' in tests, use '%clang_cl'. ***\""""))
         self.config.substitutions.append(
             (' clang -cc1 -analyze ',
def use_lld(self, additional_tool_dirs=[], required=True):
         ld_lld = self.use_llvm_tool('ld.lld', required=required)
         lld_link = self.use_llvm_tool('lld-link', required=required)
         ld64_lld = self.use_llvm_tool('ld64.lld', required=required)
         wasm_ld = self.use_llvm_tool('wasm-ld', required=required)
 
         was_found = ld_lld and lld_link and ld64_lld and wasm_ld
         tool_substitutions = []
         if ld_lld:
-            tool_substitutions.append(ToolSubst('ld\.lld', command=ld_lld))
+            tool_substitutions.append(ToolSubst(r'ld\.lld', command=ld_lld))
         if lld_link:
             tool_substitutions.append(ToolSubst('lld-link', command=lld_link))
         if ld64_lld:
-            tool_substitutions.append(ToolSubst('ld64\.lld', command=ld64_lld))
+            tool_substitutions.append(ToolSubst(r'ld64\.lld', command=ld64_lld))
         if wasm_ld:
             tool_substitutions.append(ToolSubst('wasm-ld', command=wasm_ld))
         self.add_tool_substitutions(tool_substitutions)
         return was_found