Buffer for Dynamic Text was allocated too late

While drawing a dynamic text, there was a memset() in the beginning of QSafeTextLayout::update() method, which had NULL pointer, but luckily 0 length too, so no memory was actually touched. The reason for NULL and 0 is that the memory was actually allocated later in drawGlyph() method.

Neither Valgrind nor Polyspace saw this as a problem as NULL pointer was not dereferenced and nothing bad happened, but is was still not the intended functionality.

Found when replacing the memset() with a loop to copy m_fillColor to the allocated dynamic text bitmap.