Alpine APKBUILD matched license text is incorrect with --package

For instance, this APKBUILD:
```shell
# Contributor: Oliver Smith
# Maintainer: Natanael Copa
pkgname=linux-firmware
pkgver=20201218
pkgrel=0
pkgdesc="firmware files for linux"
url="https://git.kernel.org/?p=linux/kernel/git/firmware/linux-firmware.git;a=summary"
arch="all"
license="custom:multiple"
```
will yield a correct extracted_license_statement and an incorrect matched text
```JSON
{
"type": "alpine",
"namespace": null,
"name": "linux-firmware",
"version": "20201218-r0",
.......
"declared_license_expression": "unknown-license-reference",
"declared_license_expression_spdx": "LicenseRef-scancode-unknown-license-reference",
"license_detections": [
{
"license_expression": "unknown-license-reference",
"license_expression_spdx": "LicenseRef-scancode-unknown-license-reference",
"matches": [
{
"license_expression": "unknown-license-reference",
"license_expression_spdx": "LicenseRef-scancode-unknown-license-reference",
"from_file": null,
"start_line": 1,
"end_line": 1,
"matcher": "1-hash",
"score": 100.0,
"matched_length": 5,
"match_coverage": 100.0,
"rule_relevance": 100,
"rule_identifier": "unknown-license-reference_421.RULE",
"rule_url": "https://github.com/nexB/scancode-toolkit/tree/develop/src/licensedcode/data/rules/unknown-license-reference_421.RULE",
"matched_text": "licenseref-scancode-unknown-license-reference"
}
],
"identifier": "unknown_license_reference-9aed0e23-afe9-af3b-c9a4-e4121dca0810"
}
],
"other_license_expression": null,
"other_license_expression_spdx": null,
"other_license_detections": [],
"extracted_license_statement": "custom:multiple",
.......

```

The ` "matched_text": "licenseref-scancode-unknown-license-reference"` is incorrect .... this is not what the extracted license statement contains.