sys: Split up syscall.lo 'echo's

sys: Split up syscall.lo 'echo's

Currently we echo a string to syscall.lo to generate it. However,
'echo' is often a shell builtin, and some shells (such as bash) do not
interpret escape codes like \n unless the -e option is given. So, this
results in syscall.lo containing a single commented line, which
results in .libs/libafsrpc_sys.a not getting created, which later on
causes errors.

Instead, just split the syscall.lo generation into separate echo
invocations, to make sure we work everywhere.

Change-Id: I8a6ed42a0837086de604be0936d830f0f4558ebf
Reviewed-on: http://gerrit.openafs.org/8202
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>