llvm-wrapper: adapt for LLVM 19 API change

No functional changes intended.

The instrprof_mcdc_condbitmap_update intrinsic was dropped in LLVM 19:
* llvm/llvm-project@85a7bba

compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp

@@ -1576,11 +1576,11 @@ extern "C" LLVMValueRef LLVMRustGetInstrProfMCDCTVBitmapUpdateIntrinsic(LLVMModu
 }
 
 extern "C" LLVMValueRef LLVMRustGetInstrProfMCDCCondBitmapIntrinsic(LLVMModuleRef M) {
-#if LLVM_VERSION_GE(18, 0)
+#if LLVM_VERSION_GE(18, 0) && LLVM_VERSION_LT(19, 0)
   return wrap(llvm::Intrinsic::getDeclaration(
       unwrap(M), llvm::Intrinsic::instrprof_mcdc_condbitmap_update));
 #else
-  report_fatal_error("LLVM 18.0 is required for mcdc intrinsic functions");
+  report_fatal_error("The instrprof_mcdc_condbitmap_update only exists in LLVM 18");
 #endif
 }