Do not destroy SVG data in XCCDF elements that allow XHTML (and SVG) content

SVG is allowed in XHTML so we shall pass it through the guide and report
generating machinery.
Bump soname from 8.2.3 to 8.3.0

One new symbol has been added:

    xccdf_policy_get_value_of_item
openscap-1.0.9
trac#385: Missing version should not be fatal

We already handle @comment similarly.

Addressing:
    #0  0x000000391c03a997 in ____strtoll_l_internal () from /lib64/libc.so.6
    #1  0x000000391c0371d0 in atoi () from /lib64/libc.so.6
    #2  0x00007ffff7d20f52 in oval_test_parse_tag (reader=0x61eac0, context=0x7fffffffd840, usr=0x0) at oval_test.c:402
    #3  0x00007ffff7d151f4 in oval_parser_parse_tag (reader=0x61eac0, context=0x7fffffffd840, tag_parser=0x7ffff7d20d23 <oval_test_parse_tag>, user=0x0) at oval_parser.c:59
    #4  0x00007ffff7d156c8 in oval_definition_model_parse (reader=0x61eac0, context=0x7fffffffd840) at oval_parser.c:177
    #5  0x00007ffff7d057fb in oval_definition_model_merge (model=0x61ec20, file=0x61c9f0 "/var/tmp/1.xml") at oval_defModel.c:245
    #6  0x00007ffff7d056aa in oval_definition_model_import (file=0x61c9f0 "/var/tmp/1.xml") at oval_defModel.c:214
    #7  0x0000000000409c8c in app_evaluate_oval (action=0x7fffffffd990) at oscap-oval.c:390
    #8  0x0000000000407d21 in oscap_module_call (action=0x7fffffffd990) at oscap-tool.c:261
    #9  0x000000000040819e in oscap_module_process (module=0x616f00 <OVAL_EVAL>, argc=5, argv=0x7fffffffdc08) at oscap-tool.c:346
    #10 0x0000000000406b57 in main (argc=5, argv=0x7fffffffdc08) at oscap.c:79
Merge branch 'maint-1.0'