libexec vs. lib issue

[Jan Šmydke <jan.smydke%jh-inst.cas.cz@localhost>]

Hello,

recently I experienced a problem on Linux amd64 that libraries were
installed to "lib64" instead of "lib" directory. This was successfully
resolved by setting "SET_LIBDIR=yes" (thanks to Aleksey Cheusov).

Now I face to a similar issue that files are installed to "lib" instead
of "libexec" directory.

Could anyone, please, help?

Thanks
JS