baremetal: Implement cpp.prefixHeaders for SDCC compiler
baremetal: Implement cpp.prefixHeaders for SDCC compiler

The SDCC compiler has the -Wp option which allows to pass
the preprocessor options directly to the sdcpp preprocessor.

Change-Id: I3b2c1bd5accb1bbdc7f7d7309384efc6649f4cfd
Reviewed-by: Ivan Komissarov <96f14e4d07227e958f51f7d2898113639e9498d9@gmail.com>

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