CMake: Remove starting `.` from GODOTCPP_SUFFIX #572

Job	Run time
📊 Static Checks / Format (clang-format, ruff format, file format)	16s
Analyze Changes	10s
🛠️ SCons CI	0s
🛠️ CMake CI / 🐧 Linux (GCC, Makefiles)	1m 26s
🛠️ CMake CI / 🏁 Windows (x86_64, MSVC)	2m 5s
🛠️ CMake CI / 🤖 Android (arm64, Ninja)	50s
🛠️ CMake CI / 🏁 Windows (x86_64, MinGW, Ninja)	1m 57s
🛠️ CMake CI / 🌐 Web (wasm32, Ninja)	58s
🛠️ CMake CI / 🍏 iOS (arm64, XCode)	1m 2s
🛠️ CMake CI / 🍎 macOS (universal, Makefiles)	3m 47s
	12m 31s

Provide feedback