Fix make distclean

There is no distclean target defined in doc, so this previously failed
fix #3221
fix #3220
Merge pull request #3216 from simonster/distclean

Fix make distclean
fix #3206
the compiler is now good enough at varargs to handle generic multi-argument
operators recursively.
Merge branch 'master' of github.com:JuliaLang/julia
remove reference to E"" strings from manual. fixes #3222
apply fix #3153 to openlibm also
do ARCH autodetection based upon compiler instead of host (fix #3153)
Merge branch 'master' into master-mkl