Magic tests fix (#1714)

* test: Relax pe32 condition in magic tests

Turns out different versions of libmagic return different file
identification for the PE32 sample in magic tests. Relax this condition
to the common part of the identification to make tests less reliant on
the testing platform.

* test: Relax macho condition in magic tests

tests/test-magic.c

@@ -23,15 +23,15 @@ int main(int argc, char** argv)
 
   assert_true_rule_blob(
       "import \"magic\" rule test { condition: \
-      magic.type() contains \"PE32\" and \
+      magic.type() contains \"MS-DOS executable\" and \
       magic.mime_type() == \"application/x-dosexec\" }",
       PE32_FILE);
 
   // Test case for https://github.com/VirusTotal/yara/issues/1663
   assert_true_rule_blob(
       "import \"magic\" rule test { condition: \
       magic.type() contains \"Mach-O\" and \
-      magic.mime_type() == \"application/x-mach-binary\" and \
+      (magic.mime_type() == \"application/x-mach-binary\" or magic.mime_type() == \"application/octet-stream\") and \
       magic.type() contains \"Mach-O\"}",
       MACHO_X86_FILE);