linux-user: Add strace support for printing argument of syscalls used for extended attributes

This patch implements strace argument printing functionality for following syscalls:

    *getxattr, lgetxattr, fgetxattr - retrieve an extended attribute value

        ssize_t getxattr(const char *path, const char *name, void *value, size_t size)
        ssize_t lgetxattr(const char *path, const char *name, void *value, size_t size)
        ssize_t fgetxattr(int fd, const char *name, void *value, size_t size)
        man page: https://www.man7.org/linux/man-pages/man2/getxattr.2.html

    *listxattr, llistxattr, flistxattr - list extended attribute names

        ssize_t listxattr(const char *path, char *list, size_t size)
        ssize_t llistxattr(const char *path, char *list, size_t size)
        ssize_t flistxattr(int fd, char *list, size_t size)
        man page: https://www.man7.org/linux/man-pages/man2/listxattr.2.html

    *removexattr, lremovexattr, fremovexattr - remove an extended attribute

         int removexattr(const char *path, const char *name)
         int lremovexattr(const char *path, const char *name)
         int fremovexattr(int fd, const char *name)
         man page: https://www.man7.org/linux/man-pages/man2/removexattr.2.html



Implementation notes:

    All of the syscalls have strings as argument types and thus a separate
    printing function was stated in file "strace.list" for every one of them.
    All of these printing functions were defined in "strace.c" using existing
    printing functions for appropriate argument types:
       "print_string()" - for (const char*) type
       "print_pointer()" - for (char*) and (void *) type
       "print_raw_param()" for (int) and (size_t) type
    Syscalls "getxattr()" and "lgetxattr()" have the same number and type of
    arguments and thus their print functions ("print_getxattr", "print_lgetxattr")
    share a same definition. The same statement applies to syscalls "listxattr()"
    and "llistxattr()".
    Function "print_syscall_ret_listxattr()" was added to print the returned list
    of extended attributes for syscalls "print_listxattr(), print_llistxattr() and
    print_flistxattr()".

Signed-off-by: Filip Bozuta <Filip.Bozuta@syrmia.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20200619123331.17387-4-filip.bozuta@syrmia.com>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>