Fix bug in linker flag generation for static builds of Qt on iOS.
Fix bug in linker flag generation for static builds of Qt on iOS.

Resolves "ld: library not found for -lQtPlatformSupport_debug".

Change-Id: I0ba76134b06452afb319b10bc6a9e28c9e17f4d4
Reviewed-by: Christian Kandeler <3aa99dcdd3f0cac61fb81c2a11771c0cc2497607@theqtcompany.com>

qt-labs/qbs,gatzka/qt-labs-qbs,gatzka/qt-labs-qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,gatzka/qt-labs-qbs,qt-labs/qbs,gatzka/qt-labs-qbs,gatzka/qt-labs-qbs,gatzka/qt-labs-qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qt-labs/qbs,gatzka/qt-labs-qbs,qt-labs/qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qtproject/qt-labs-qbs,qt-labs/qbs,qt-labs/qbs,qtproject/qt-labs-qbs