[Build] Update native libraries build instruction

imgui-lwjgl3/build.gradle

@@ -38,7 +38,7 @@ dependencies {
 task startExample(type: JavaExec, dependsOn: build) {
     main = 'ImGuiGlfwExample'
     classpath = sourceSets.test.runtimeClasspath
-    jvmArgs = ['-Djava.library.path=../bin']
+    jvmArgs = ["-Djava.library.path=${System.getProperty('libPath', '../bin')}"]
 
     if (OperatingSystem.current().isMacOsX()) {
         jvmArgs += ['-XstartOnFirstThread', '-Djava.awt.headless=true']