Fix compile error in lemul branch (undefined reference to: nlinux32_syscalls, linux32_syscallnames)

After the changes that moved the include of linux_syscalls.c inline, rather than via the Makefile, the same was not done for linux32_syscalls.c
Apply the same treatment to linux32_syscallnames and nlinux32_syscalls as their 64bit counterparts got earlier

Differential Revision: https://reviews.freebsd.org/D1509
Approved by: dchagin
Sponsored by: ScaleEngine Inc.