Fix a check with priority issues in wbemprox

get_propval returns several codes from S_OK to WBEM_E_FAILED;
The following line seems to not be doing what is expected:

if ((hr = get_propval( view, co->index, property, pVal, pType, plFlavor ) != S_OK))

Here it assigns to hr 0 or 1, instead the returned code due to priority (!= over =).