Most of the glVertexAttrib methods (like glVertexAttrib4fv()) are only part of the compatibility profile in Qt. The only methods in the core classes (eg. QOpenGLFunctions_4_3_Core) are those for GLdouble and GLuint, older versions like QOpenGLFunctions_3_3_Core only include the GLuint methods. What is the reason for this? According to the official OpenGL reference (https://www.opengl.org/sdk/docs/man4/) all of them are part of the core profile even in the latest version.
EDIT: It's a bug in Qt and should be fixed in Qt 5.4.0
Sounds like a bug, so please report it. The versioned GL function resolvers (i.e. QOpenGLFunctions_X_Y_Profile, not QOpenGLFunctions) are automatically generated from the spec files published by Khronos, which in turn are known to have bugs.
(And, while we speak, the generator is getting upgraded to use the new XML files and have 4.4 functions).
In any case it must be investigated if it's a generator bug or a specs bug and fixed.