Log message:
(devel/R-pkgbuild) Updated from 1.0.4 to 1.0.6

(pkgsrc)
USE_LANGUAGES= c added resulting
'make test' pass with only one WARNING

(upstream)
# pkgbuild 1.0.6
* Support for RTools 40 and custom msys2 toolchains that are explicitly set
  using the `CC` Makevars (#40).

# pkgbuild 1.0.5
* `check_build_tools()` gains a `quiet` argument, to control when the message
  is displayed. The message is no longer displayed when `check_build_tools()`
  is called internally by pkgbuild functions. (#83)