Fix recog verify external example support

[mkienow-r7]

Description

Fixes recog_verify external example support (_filename).

Example

Data

$ tree external-example-files
external-example-files
├── thingA
│   ├── file1
│   └── file2.txt
└── thingA.xml

thingA.xml:

<?xml version='1.0' encoding='UTF-8'?>
<fingerprints matches="thing">
  <fingerprint pattern="x64|amd64|x86_64">
    <description>x64 (x86_x64)</description>
    <example _filename="file1"></example>
    <example _filename="file2.txt"></example>
    <param pos="0" name="os.arch" value="x86_64"/>
  </fingerprint>
</fingerprints

thingA/file1:

Linux claw 3.11.0-15-generic #23-Ubuntu SMP Mon Dec 9 18:17:04 UTC 2013 x86_64 x86_64 x86_64 GNU/Linux

thingA/file2.txt:

Linux dev 4.19.0-6-amd64 #1 SMP Debian 4.19.67-2+deb10u1 (2019-09-20) x86_64 GNU/Linux

Before Fix

$ ./bin/recog_verify external-example-files/*.xml
external-example-files/thingA.xml: FAIL: 'x64 (x86_x64)' failed to find expected capture group _filename 'file1'. Result was
external-example-files/thingA.xml: FAIL: 'x64 (x86_x64)' failed to find expected capture group _filename 'file2.txt'. Result was
external-example-files/thingA.xml: SUMMARY: Test completed with 0 successful, 0 warnings, and 2 failures

After Fix

$ ./bin/recog_verify external-example-files/*.xml
external-example-files/thingA.xml: SUMMARY: Test completed with 2 successful, 0 warnings, and 0 failures

Motivation and Context

Fixing an issue

How Has This Been Tested?

• ./bin/recog_verify on the example data described above
• rake tests

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist:

• I have updated the documentation accordingly (or changes are not required).
• I have added tests to cover my changes (or new tests are not required).
• All new and existing tests passed.

[hdm]

Thank you!