improve: use all threads for compiling (#118)

This commit speeds up the build process by almost 50% when building with github actions by using all system threads to compile ReZygisk.

loader/build.gradle.kts

@@ -56,6 +56,7 @@ android {
         externalNativeBuild.cmake {
             arguments += "-DANDROID_STL=none"
             arguments += "-DLSPLT_STANDALONE=ON"
+            arguments += "-DCMAKE_BUILD_PARALLEL_LEVEL=${Runtime.getRuntime().availableProcessors()}"
             cFlags("-std=c18", *defaultCFlags)
             cppFlags("-std=c++20", *defaultCFlags)
             ccachePath?.let {