The Qbs generator must export cxxFlags to cpp.cxxFlags
The cpp_info.cxxFlags must be exported to the cpp.cxxFlags in Qbs.
The cpp.cppFlags property has a different meaning  (C preprocessor
flags).
Fixes
@@ -40,7 +40,7 @@ class QbsGenerator(Generator):
' cpp.systemIncludePaths: [{deps.bin_paths}]\n'
' cpp.dynamicLibraries: [{deps.libs}]\n'
' cpp.defines: [{deps.defines}]\n'
- ' cpp.cppFlags: [{deps.cxxflags}]\n' # TODO: cppFlags -> cxxFlags?
+ ' cpp.cxxFlags: [{deps.cxxflags}]\n'
' cpp.cFlags: [{deps.cflags}]\n'
' cpp.linkerFlags: [{deps.linkerFlags}]\n'
' }}\n'
