zdtm: fix collecting libraries on Alpine Linux

Here is an example of ldd output:

/musl # ldd /usr/lib/libxtables.so.12
	ldd (0x7fae8e06c000)
	libc.musl-x86_64.so.1 => ldd (0x7fae8e06c000)

We need to skip the "ldd (0x7fae8e06c000)" line.
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

test/zdtm.py

@@ -183,7 +183,7 @@ class ns_flavor:
 
 	def __copy_libs(self, binary):
 		ldd = subprocess.Popen(["ldd", binary], stdout = subprocess.PIPE)
-		xl = re.compile('^(linux-gate.so|linux-vdso(64)?.so|not a dynamic)')
+		xl = re.compile('^(linux-gate.so|linux-vdso(64)?.so|not a dynamic|.*\s*ldd\s)')
 
 		# This Mayakovsky-style code gets list of libraries a binary
 		# needs minus vdso and gate .so-s