shims/super/cc: run in bash shell

[dawidd6]

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your changes? Here's an example.
• Have you successfully run brew style with your changes locally?
• Have you successfully run brew typecheck with your changes locally?
• Have you successfully run brew tests with your changes locally?

---

Should fix errors like this one:

/home/linuxbrew/.linuxbrew/Homebrew/Library/Homebrew/shims/linux/super/g++-5: 3: /home/linuxbrew/.linuxbrew/Homebrew/Library/Homebrew/shims/linux/super/g++-5: [[: not found

I don't know if there is any special reason we run this particular shim via plain sh.

Found here: https://github.com/Homebrew/homebrew-core/pull/85282/checks?check_run_id=3624010217

Bug introduced in: #12044

[BrewTestBot]

Review period will end on 2021-09-20 at 20:17:21 UTC.

[Bo98]

Hmm:

  expected that /home/linuxbrew/.linuxbrew/Homebrew/Library/Homebrew/shims/super/cc is a valid Bash file:
  /home/linuxbrew/.linuxbrew/Homebrew/Library/Homebrew/shims/super/cc: line 28: syntax error near unexpected token `('
  /home/linuxbrew/.linuxbrew/Homebrew/Library/Homebrew/shims/super/cc: line 28: `  CXX_REGEX = /(?:c|g|clang)\+\+/.freeze'

[BrewTestBot]

Review period skipped due to critical label.

[XuehaiPan]

Probably similar issue for shims/mac/super/pkg-config. This is the last shell file that uses shebang #!/bin/sh in this repo.

brew/Library/Homebrew/shims/mac/super/pkg-config

Lines 1 to 10 in bfd6050

	#!/bin/sh
	# HOMEBREW_OPT and HOMEBREW_SDKROOT are set by extend/ENV/super.rb
	# shellcheck disable=SC2154
	pkg_config="${HOMEBREW_OPT}/pkg-config/bin/pkg-config"
	if [[ -z "${HOMEBREW_SDKROOT}" ]]
	then
	exec "${pkg_config}" "$@"
	fi