Everywhere: Rename ASSERT => VERIFY

(...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED)

Since all of these checks are done in release builds as well,
let's rename them to VERIFY to prevent confusion, as everyone is
used to assertions being compiled out in release.

We can introduce a new ASSERT macro that is specifically for debug
checks, but I'm doing this wholesale conversion first since we've
accumulated thousands of these already, and it's not immediately
obvious which ones are suitable for ASSERT.

Userland/Libraries/LibPthread/pthread.cpp

@@ -92,7 +92,7 @@ static int create_thread(pthread_t* thread, void* (*entry)(void*), void* argumen
 
     push_on_stack(argument);
     push_on_stack((void*)entry);
-    ASSERT((uintptr_t)stack % 16 == 0);
+    VERIFY((uintptr_t)stack % 16 == 0);
 
     // Push a fake return address
     push_on_stack(nullptr);
@@ -107,7 +107,7 @@ static int create_thread(pthread_t* thread, void* (*entry)(void*), void* argumen
 {
     KeyDestroyer::destroy_for_current_thread();
     syscall(SC_exit_thread, code);
-    ASSERT_NOT_REACHED();
+    VERIFY_NOT_REACHED();
 }
 
 int pthread_self()
@@ -485,7 +485,7 @@ static int cond_wait(pthread_cond_t* cond, pthread_mutex_t* mutex, const struct
 int pthread_cond_wait(pthread_cond_t* cond, pthread_mutex_t* mutex)
 {
     int rc = cond_wait(cond, mutex, nullptr);
-    ASSERT(rc == 0);
+    VERIFY(rc == 0);
     return 0;
 }
 
@@ -516,7 +516,7 @@ int pthread_cond_signal(pthread_cond_t* cond)
     u32 value = cond->previous + 1;
     cond->value = value;
     int rc = futex(&cond->value, FUTEX_WAKE, 1, nullptr, nullptr, 0);
-    ASSERT(rc >= 0);
+    VERIFY(rc >= 0);
     return 0;
 }
 
@@ -525,7 +525,7 @@ int pthread_cond_broadcast(pthread_cond_t* cond)
     u32 value = cond->previous + 1;
     cond->value = value;
     int rc = futex(&cond->value, FUTEX_WAKE, INT32_MAX, nullptr, nullptr, 0);
-    ASSERT(rc >= 0);
+    VERIFY(rc >= 0);
     return 0;
 }
 
@@ -874,15 +874,15 @@ int pthread_rwlockattr_destroy(pthread_rwlockattr_t*)
 }
 int pthread_rwlockattr_getpshared(const pthread_rwlockattr_t* __restrict, int* __restrict)
 {
-    ASSERT_NOT_REACHED();
+    VERIFY_NOT_REACHED();
 }
 int pthread_rwlockattr_init(pthread_rwlockattr_t*)
 {
-    ASSERT_NOT_REACHED();
+    VERIFY_NOT_REACHED();
 }
 int pthread_rwlockattr_setpshared(pthread_rwlockattr_t*, int)
 {
-    ASSERT_NOT_REACHED();
+    VERIFY_NOT_REACHED();
 }
 
 int pthread_atfork(void (*prepare)(void), void (*parent)(void), void (*child)(void))