The ICON qmake variable is implemented in the Xcode generator through
the ProjectBuilderSources::files() function, where we append the icon
to SOURCES (for some reason). This means we can't exclude non-object
sources when writing out PBXBuildFile entries, as the icon file entry
is referenced later on in the bundle resources phase.
This is a partial revert of 66f6e5b162 which introduced the broken
logic.
Change-Id: I120d2325165a1eefd3961a9162e9e5eb3a576c36
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@digia.com>
84c2749767