The patches attached below fix several minor issues with building pinentry with mingw.org's MinGW on MS-Windows:
- symlink command that's part of "make install" that fails to use $(EXEEXT) on the target
- unnecessary inclusion of iconv.h and langinfo.h in pinentry-curses.c, which fails the compilation when these headers are not available
- compilation warning in pinentry-curses.c due to type mismatch
- a simple replacement for the missing nl-langinfo function in pinentry.c
- compiler warnings in secmem.c due to variables used only in some configurations
- link error buulding pinentry-w32.exe because libiconv is not on the link command line