musl doesn't support dlclose, so don't test it.

--- rttr-0.9.6/src/unit_tests/misc/library_test.cpp.old	2018-03-26 21:31:07.000000000 +0000
+++ rttr-0.9.6/src/unit_tests/misc/library_test.cpp	2019-04-19 00:10:52.775313358 +0000
@@ -71,7 +71,7 @@
         CHECK(lib.get_types().size()             == 0);
         CHECK(lib.get_global_properties().size() == 0);
         CHECK(lib.get_global_methods().size()    == 0);
-        CHECK(does_plugin_type_exist()           == false);
+        //CHECK(does_plugin_type_exist()           == false);
     }
 
     SECTION("negative test")
@@ -102,7 +102,7 @@
 #else
     #error "Don't know library suffix on this plattform!"
 #endif
-        CHECK(does_plugin_type_exist()          == false);
+        //CHECK(does_plugin_type_exist()          == false);
         CHECK(lib.load()                        == true);
         REQUIRE(lib.get_error_string().empty()  == true);
         CHECK(does_plugin_type_exist()          == true);
@@ -110,7 +110,7 @@
         CHECK(lib.get_error_string().empty()    == true);
         CHECK(lib.unload()                      == true);
 
-        CHECK(does_plugin_type_exist()          == false);
+        //CHECK(does_plugin_type_exist()          == false);
     }
 }
 
@@ -122,19 +122,19 @@
     {
         library lib(library_name);
 
-        CHECK(does_plugin_type_exist()              == false);
+        //CHECK(does_plugin_type_exist()              == false);
         CHECK(lib.load()                            == true);
         CHECK(lib.load()                            == true);
 
         REQUIRE(lib.get_error_string().empty()      == true);
         CHECK(does_plugin_type_exist()              == true);
 
-        CHECK(lib.get_types().size()                > 1);
+        //CHECK(lib.get_types().size()                > 1);
         CHECK(lib.get_global_properties().size()    == 0);
         CHECK(lib.get_global_methods().size()       == 0);
 
         CHECK(lib.unload() == true);
-        CHECK(does_plugin_type_exist() == false);
+        //CHECK(does_plugin_type_exist() == false);
     }
 
     SECTION("load the same lib from different instance multiple times")
@@ -142,7 +142,7 @@
         library lib1(library_name);
         library lib2(library_name);
 
-        CHECK(does_plugin_type_exist() == false);
+        //CHECK(does_plugin_type_exist() == false);
 
         CHECK(lib1.load() == true);
         CHECK(lib2.load() == true);
@@ -156,26 +156,26 @@
 
         CHECK(lib2.unload() == true);
 
-        CHECK(does_plugin_type_exist() == false);
+        //CHECK(does_plugin_type_exist() == false);
     }
 
     SECTION("load the same lib multiple times 2xload() and 2xunload()")
     {
         library lib(library_name);
 
-        CHECK(does_plugin_type_exist() == false);
+        //CHECK(does_plugin_type_exist() == false);
 
         CHECK(lib.load() == true);
         CHECK(does_plugin_type_exist() == true);
 
         CHECK(lib.unload() == true);
-        CHECK(does_plugin_type_exist() == false);
+        //CHECK(does_plugin_type_exist() == false);
 
         CHECK(lib.load() == true);
         CHECK(does_plugin_type_exist() == true);
 
         CHECK(lib.unload() == true);
-        CHECK(does_plugin_type_exist() == false);
+        //CHECK(does_plugin_type_exist() == false);
     }
 }