Auto merge of #12299 - jimberlage:fixup-scripts, r=emilio

Fix up shell scripts

<!-- Please describe your changes on the following line: -->
This brings these two scripts in line with the style guidelines.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `__` with appropriate data: -->
- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

<!-- Either: -->
- [ ] There are tests for these changes OR
- [X] These changes do not require tests because it's a small change to bring some shell scripts in line with the style guide

<!-- Pull requests that do not address these steps are welcome, but they will require additional verification as part of the review process. -->

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ports/geckolib/gecko_bindings/tools/regen.sh

@@ -1,4 +1,12 @@
-#!/bin/bash
+#!/usr/bin/env bash
+
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+set -o errexit
+set -o nounset
+set -o pipefail
 
 if [ $# -eq 0 ]; then
   echo "Usage: $0 /path/to/gecko/objdir [other-regen.py-flags]"
@@ -13,7 +21,8 @@ fi
 
 # Check for /usr/include
 if [ ! -d /usr/include ]; then
-  echo "/usr/include doesn't exist. Mac users may need to run xcode-select --install."
+  echo "/usr/include doesn't exist." \
+       "Mac users may need to run xcode-select --install."
   exit 1
 fi
 

ports/geckolib/gecko_bindings/tools/setup_bindgen.sh

@@ -1,4 +1,12 @@
-#!/bin/bash
+#!/usr/bin/env bash
+
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+set -o errexit
+set -o nounset
+set -o pipefail
 
 # Run in the tools directory.
 cd "$(dirname $0)"
@@ -12,7 +20,8 @@ fi
 
 # Make sure we have llvm38.
 if [ ! -x "$(command -v clang-3.8)" ]; then
-    echo "llmv38 must be installed. Mac users should |brew install llvm38|, Linux varies by distro."
+    echo "llmv38 must be installed." \
+         "Mac users should |brew install llvm38|, Linux varies by distro."
     exit 1
 fi