test: replace use of pcre grep with awk

Unfortunately, grep -P is not ubiquitous, so use awk with two regexps to
simulate the negative forward lookup in the grep -P expression.

Using awk doesn't really make it too unreadable, as using boolean operators
such as && and || might actually make it more intuitive than the extended
regexp.

Tested:
- sudo make -C test zdtm_ns
- sudo make -C test zdtm_nons

Signed-off-by: Filipe Brandenburger <filbranden@google.com>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
test: enhance library lookup when building mntns root

Use a single awk script to parse the ldd output. Filter out other cases that
are clearly not libraries, such as static builds ("not a dynamic executable")
and linux-gate.so. Make the grep for vdso more specific into linux-vdso.so.

Tested:
- sudo test/zdtm.sh '^ns/.*'

Signed-off-by: Filipe Brandenburger <filbranden@google.com>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
zdtm: sort .gitignore entries

Signed-off-by: Filipe Brandenburger <filbranden@google.com>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
zdtm: add missing entries to zdtm .gitignore

Signed-off-by: Filipe Brandenburger <filbranden@google.com>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>