Bug 2955. Workaround for lack of atomic operations in GCCE standard libraries (fall back to default use of Mutex)
!isEmpty(QMAKE_MAC_SDK) {
!macx-xcode:!macx-pbuilder {
QMAKE_CFLAGS += -isysroot $$QMAKE_MAC_SDK
QMAKE_OBJECTIVE_CFLAGS += -isysroot $$QMAKE_MAC_SDK
QMAKE_CXXFLAGS += -isysroot $$QMAKE_MAC_SDK
QMAKE_LFLAGS += -Wl,-syslibroot,$$QMAKE_MAC_SDK
}
}