[[ http://pubs.opengroup.org/onlinepubs/9699919799/functions/strcasecmp.html | The POSIX definition for strcasecmp ]] states that it is in the <strings.h> include file, not <string.h>. This causes the following build error on the musl libc:
> ```/usr/src/packages/user/kcalcore/src/kcalcore-17.08.1/src/versit/vcc.y: In function 'enterAttr':
> ```/usr/src/packages/user/kcalcore/src/kcalcore-17.08.1/src/versit/vcc.y:485:9: error: implicit definition of function 'strcasecmp' [-Werror=implicit-function-definition]```
This patch fixes this error (and a few others later on in the file).