LibM: Add dummy implementations of roundf() and ceilf()

I though I could just use __builtin_roundf() and __builtin_ceilf() but
it seems like I can't, as they just become calls to roundf and ceilf.

Libraries/LibM/math.cpp

@@ -273,4 +273,17 @@ long double frexpl(long double, int*)
     ASSERT_NOT_REACHED();
     return 0;
 }
+
+float roundf(float value)
+{
+    // FIXME: Please fix me. I am sad.
+    return (int)value;
+}
+
+float ceilf(float value)
+{
+    // FIXME: Please fix me. I am sad.
+    return (int)value;
+}
+
 }