Convert macros from plain QByteArray to a vector of structs

The old code model expected the macros as C++ formatted text
("#define Foo 42) but newer targets like the Clang codemodel expect key
value arguments like "-DFoo=42". So instead of parsing the text again and
again we use an abstract data description.

Task-number: QTCREATORBUG-17915
Change-Id: I0179fd13c48a581e91ee79bba9d42d501c26f19f
Reviewed-by: Tobias Hunger <tobias.hunger@qt.io>

src/plugins/cpptools/cpptoolsunittestfiles.pri

@@ -1,11 +1,7 @@
-# Currently there are no tests for the project explorer plugin, but we include
-# headers from it that needs to have the export/import adapted for Windows.
 shared {
     DEFINES += CPPTOOLS_LIBRARY
-    DEFINES += PROJECTEXPLORER_LIBRARY
 } else {
     DEFINES += CPPTOOLS_STATIC_LIBRARY
-    DEFINES += PROJECTEXPLORER_STATIC_LIBRARY
 }
 
 HEADERS += \