Природа сего бага мне вполне ясна. Вопрос в том, как его обойти.
У ld есть специальные опции:
-( archives -)
--start-group archives --end-group
The archives should be a list of archive files. They may be either
explicit file names, or -l options.
The specified archives are searched repeatedly until no new unde-
fined references are created. Normally, an archive is searched
only once in the order that it is specified on the command line.
If a symbol in that archive is needed to resolve an undefined sym-
bol referred to by an object in an archive that appears later on
the command line, the linker would not be able to resolve that ref-
erence. By grouping the archives, they all be searched repeatedly
until all possible references are resolved.
Using this option has a significant performance cost. It is best
to use it only when there are unavoidable circular references
between two or more archives.
Но непонятно что написать в pro-файле, чтобы qmake сгенерил соответствующую командную строку.