Use oscap_streq instead of oscap_strcmp
Use oscap_streq instead of oscap_strcmp

We are interested in checking if the strings are equal or not equal.
We are not interested in lexicographical comparison of the strings.
We should use type compatible functions because calling incompatible
functions is undefined behavior in C.

Addressing:
/home/jcerny/openscap/src/XCCDF/resolve.c: In function ‘xccdf_resolve_group’:
/home/jcerny/openscap/src/XCCDF/resolve.c:289:85: warning: cast between incompatible function types from ‘int (*)(const char *, const char *)’ to ‘_Bool (*)(void *, void *)’ [-Wcast-function-type]
  289 |  xccdf_resolve_appendlist(&child->sub.group.conflicts, parent->sub.group.conflicts, (oscap_cmp_func)oscap_strcmp, (oscap_clone_func)oscap_strdup, false);
      |                                                                                     ^
/home/jcerny/openscap/src/XCCDF/resolve.c: In function ‘xccdf_resolve_rule’:
/home/jcerny/openscap/src/XCCDF/resolve.c:317:83: warning: cast between incompatible function types from ‘int (*)(const char *, const char *)’ to ‘_Bool (*)(void *, void *)’ [-Wcast-function-type]
  317 |  xccdf_resolve_appendlist(&child->sub.rule.conflicts, parent->sub.rule.conflicts, (oscap_cmp_func)oscap_strcmp, (oscap_clone_func)oscap_strdup, false);
      |

OpenSCAP/openscap,OpenSCAP/openscap,redhatrises/openscap,OpenSCAP/openscap,OpenSCAP/openscap,OpenSCAP/openscap,redhatrises/openscap,redhatrises/openscap,OpenSCAP/openscap,redhatrises/openscap,redhatrises/openscap,redhatrises/openscap