Add -Cllvm-args="--switch-to-lookup=true" to Cargo config (#1873)

add -Cllvm-args="--switch-to-lookup=true" to .cargo/config.toml

Author: Robbepop

.cargo/config.toml

@@ -0,0 +1,11 @@
+[build]
+rustflags = [
+    # This flag is extremely important to make LLVM _not_ pessimize
+    # codegen for the conversion of `OpCode` to execution handler.
+    # This resulted in massive wins for compile-time and execution
+    # performance, especially when `indirect-dispatch` is enabled.
+    #
+    # Tested with: Rust 1.96 using LLVM 22.1.2
+    "-C",
+    "llvm-args=--switch-to-lookup=true",
+]