Perform explicit garbage collection before every backupAndHook

Gives GC a chance to do its work before every hook so there is less chance
it gets in the way in the middle of hooking procedure which does critical
memory block operations.
Attempts to fix GC related crashes such as those reported in #127

Bridge/src/main/java/com/elderdrivers/riru/xposed/core/HookMain.java

@@ -111,6 +111,7 @@ public class HookMain {
         if (backup != null) {
             HookMethodResolver.resolveMethod(hook, backup);
         }
+        Runtime.getRuntime().gc();
         if (!backupAndHookNative(target, hook, backup)) {
             throw new RuntimeException("Failed to hook " + target + " with " + hook);
         }