LibPthread: Add implementation for pthread_mutexattr_gettype

Author: https://github.com/gunnarbeutner
Commit: https://github.com/SerenityOS/serenity/commit/6e80b9fd01d
Pull-request: https://github.com/SerenityOS/serenity/pull/6959

Userland/Libraries/LibPthread/pthread.cpp

@@ -196,6 +196,12 @@ int pthread_mutexattr_settype(pthread_mutexattr_t* attr, int type)
     return 0;
 }
 
+int pthread_mutexattr_gettype(pthread_mutexattr_t* attr, int* type)
+{
+    *type = attr->type;
+    return 0;
+}
+
 int pthread_attr_init(pthread_attr_t* attributes)
 {
     auto* impl = new PthreadAttrImpl {};

Userland/Libraries/LibPthread/pthread.h

@@ -112,6 +112,7 @@ int pthread_detach(pthread_t);
 int pthread_equal(pthread_t, pthread_t);
 int pthread_mutexattr_init(pthread_mutexattr_t*);
 int pthread_mutexattr_settype(pthread_mutexattr_t*, int);
+int pthread_mutexattr_gettype(pthread_mutexattr_t*, int*);
 int pthread_mutexattr_destroy(pthread_mutexattr_t*);
 
 int pthread_setname_np(pthread_t, const char*);