[clang][CIR] Merge the mlir::cir namespace into cir (#115386)

https://github.com/llvm/clangir/issues/1025 discusses the motivation.
The mechanical parts of this change were done via:

find clang \( -name '*.h' -o -name '*.cpp' -o -name '*.td' \) -print0 |
xargs -0 perl -pi -e 's/mlir::cir/cir/g'
find clang \( -name '*.h' -o -name '*.cpp' \) -print0 | xargs -0 perl
-pi -e 's/::cir/cir/g'

There were some manual fixups and a clang-format run afterwards.

1 files changed, 1 insertions, 1 deletions

diff --git a/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp b/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
index 60fde03..3f95a1e 100644
--- a/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
+++ b/clang/lib/FrontendTool/ExecuteCompilerInvocation.cpp
@@ -67,7 +67,7 @@ CreateFrontendBaseAction(CompilerInstance &CI) {
   case EmitBC:                 return std::make_unique<EmitBCAction>();
   case EmitCIR:
 #if CLANG_ENABLE_CIR
-    return std::make_unique<::cir::EmitCIRAction>();
+    return std::make_unique<cir::EmitCIRAction>();
 #else
     llvm_unreachable("CIR suppport not built into clang");
 #endif