mako: do not use global cpp flag

at least the result is the same but let us user the
propper way like we do it with all flags and do not
set if over a global cpp flag

Change-Id: I1b7a229226af96cdfd294752823939a2cf870649
Merge branch 'pa/jb43-jwr'
Merge remote-tracking branch 'upstream/jb43' into jb43