cwebp.c: fix a missing \n
cwebp.c: fix a missing \n

+ lot more coverage of exotic options and combinations

Change-Id: I4d8e571a6d94023af9848a2bbd98edda05a54f33

PKRoma/libwebp,PKRoma/libwebp,webmproject/libwebp,webmproject/libwebp,PKRoma/libwebp,webmproject/libwebp,PKRoma/libwebp,webmproject/libwebp,PKRoma/libwebp,PKRoma/libwebp,webmproject/libwebp