Tests: Build automatically, fix compilation errors

Author: https://github.com/BenWiederhake
Commit: 29eceebdbf
Pull-request: https://github.com/SerenityOS/serenity/pull/2947

Userland/Tests/Kernel/path-resolution-race.cpp

@@ -0,0 +1,16 @@
+#include <unistd.h>
+#include <sys/stat.h>
+
+int main()
+{
+    if (!fork()) {
+        for (;;) {
+            mkdir("/tmp/x", 0666);
+            rmdir("/tmp/x");
+        }
+    }
+    for (;;) {
+        chdir("/tmp/x");
+    }
+    return 0;
+}