QbsProjectManager: Fix cross-compiling with clang

In order to use a generic clang as a cross-compiler, we have to pass "-
target" in the "platform codegen flags" in the toolchain settings.
However, qbs errors out when that flag is used directly, so we need to
filter it out along with "-arch".

Change-Id: Ide83115b046bc53c330e86b5d5715640a4c5ed98
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/qbsprojectmanager/defaultpropertyprovider.cpp

@@ -233,8 +233,7 @@ static void filterCompilerLinkerFlags(const ProjectExplorer::Abi &targetAbi, QSt
 {
     for (int i = 0; i < flags.size(); ) {
         if (targetAbi.architecture() != ProjectExplorer::Abi::UnknownArchitecture
-                && flags[i] == QStringLiteral("-arch")
-                && i + 1 < flags.size()) {
+            && (flags[i] == "-arch" || flags[i] == "-target") && i + 1 < flags.size()) {
             flags.removeAt(i);
             flags.removeAt(i);
         } else {