96f0d3b908
Somewhat amusingly given its name, "clang.patch" applies to both 5 and 6
but is the cause of ncurses6 breakage on 6 but is required on 5...
gcc is happy in all four configurations:
5 5p 6 6p
gcc ✓ ✓ ✓ ✓
clang ✗ ✓ ✓ ✗
Which is why this commit enables the patch for 5 but not 6;
this matches behavior in Gentoo, for example.
For further simplification, we also use gcc-5 patch regardless.