OpenJDK 11 build generates `ja_JP.UTF8` manpages by default

[Benjamin Asbach]

Hello,

I currently try to improve the NixOS OpenJDK build for OpenJDK 11. I 
recognized that the make target "all" creates manpages for "ja_JP.UTF8" 
[1].

I also tried compiling OpenJDK 14 which does not generate this kind of 
output.

So I wonder if this done intentionally or a bug?

Thanks in advance
Benjamin

[1] 
https://hg.openjdk.java.net/jdk-updates/jdk11u/file/46d4984bb3c6/make/Images.gmk