[meta] Drupal-agnostic components should not be calling Drupal functions

Anything that lives in /core/lib/Drupal/Component should function independently without having Drupal installed or available. However, digitalfire has discovered that Drupal\Component\Uuid\Com (which would only be used on Windows) calls drupal_strtolower().:

class Com implements UuidInterface {
  public function generate() {
    // Remove {} wrapper and make lower case to keep result consistent.
    return drupal_strtolower(trim(com_create_guid(), '{}'));
  }
}

Grepping in Component found the following function calls in violation:

Archiver/ArchiveTar.php:            @drupal_unlink($this->_temp_tarname);
Archiver/ArchiveTar.php:            @drupal_unlink($this->_temp_tarname);
Archiver/ArchiveTar.php:            @drupal_unlink($this->_temp_tarname);
Archiver/ArchiveTar.php:            @drupal_unlink($this->_tarname);
Archiver/ArchiveTar.php:                // Changed the code to use drupal_mkdir() instead of mkdir().
Archiver/ArchiveTar.php:                if (!@drupal_mkdir($v_header['filename'], 0777)) {
Archiver/ArchiveTar.php:                  @drupal_unlink($v_header['filename']);
Archiver/ArchiveTar.php:            if (!@drupal_unlink($this->_tarname.".tmp")) {
Archiver/ArchiveTar.php:        // Changed the code to use drupal_mkdir() instead of mkdir().
Archiver/ArchiveTar.php:        if (!@drupal_mkdir($p_dir, 0777)) {
Diff/DiffEngine.php:    if (drupal_strlen($line) > $this->MAX_XREF_LENGTH()) {
Diff/DiffEngine.php:        $word = drupal_substr($word, 1);
Diff/DiffEngine.php:      if ( drupal_strlen( $line ) > $this->MAX_LINE_LENGTH() ) {
Diff/DiffEngine.php:            if (strpos($piece, '<') === 0 && drupal_substr($piece, drupal_strlen($piece) - 1) === '>') {
Diff/DiffEngine.php:            if ($piece === ' ' || (strpos($piece, '<') === 0 && drupal_substr($piece, drupal_strlen($piece) - 1) === '>' && drupal_strtolower(drupal_substr($piece, 1, 3)) != 'img')) {
Diff/DiffEngine.php:      if (strpos($piece, '<') === 0 && drupal_substr($piece, drupal_strlen($piece) - 1) === '>') {
Diff/DiffEngine.php:      elseif (isset($next) && strpos($next, '<') === 0 && drupal_substr($next, drupal_strlen($next) - 1) === '>') {
Uuid/Com.php:    return drupal_strtolower(trim(com_create_guid(), '{}'));
Uuid/Php.php:    $hex = substr(hash('sha256', drupal_random_bytes(16)), 0, 32);

Issues filed for individual components:

#1929282: Undefined function: drupal_strtolower() in com.php
#1929288: Move cryptographic functions to Crypt component
#2017345: Drupal\Component\Gettext\PoStreamReader calls get_t()
#2033193: Move PhpStorageFactory to Core
#2043773: Replace php function wrappers in file.inc with a Drupal\Core\File\FileSystem class
#2043757: Remove drupal_(string) methods out of diffengine
#2102499: Convert DiffEngine to settings