[libgames-support] Update autogen.sh from GNOME recommendation

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 4e5c055356cbedca4f8e79b9d60b5dd2299ca0df
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Sat Jul 30 20:19:27 2016 -0500

    Update autogen.sh from GNOME recommendation
    
    Our only difference is to enable the style checker
    
    https://wiki.gnome.org/Projects/GnomeCommon/Migration

 autogen.sh |   30 ++++++++++++++++--------------
 1 files changed, 16 insertions(+), 14 deletions(-)
---
diff --git a/autogen.sh b/autogen.sh
index 8e72e2d..2b33e32 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -1,10 +1,14 @@
 #!/bin/sh
 # Run this to generate all the initial makefiles, etc.
-srcdir=`dirname $0`
-test -z "$srcdir" && srcdir=.
+test -n "$srcdir" || srcdir=$(dirname "$0")
+test -n "$srcdir" || srcdir=.
 
-(test -f $srcdir/configure.ac) || {
-        echo "**Error**: Directory "\`$srcdir\'" does not look like the top-level project directory"
+olddir=$(pwd)
+
+cd $srcdir
+
+(test -f configure.ac) || {
+        echo "*** ERROR: Directory '$srcdir' does not look like the top-level project directory ***"
         exit 1
 }
 
@@ -18,27 +22,25 @@ if [ -d $srcdir/.git ]; then
         done
 fi
 
-PKG_NAME=`autoconf --trace 'AC_INIT:$1' "$srcdir/configure.ac"`
+# shellcheck disable=SC2016
+PKG_NAME=$(autoconf --trace 'AC_INIT:$1' configure.ac)
 
 if [ "$#" = 0 -a "x$NOCONFIGURE" = "x" ]; then
-        echo "**Warning**: I am going to run \`configure' with no arguments." >&2
-        echo "If you wish to pass any to it, please specify them on the" >&2
-        echo \`$0\'" command line." >&2
+        echo "*** WARNING: I am going to run 'configure' with no arguments." >&2
+        echo "*** If you wish to pass any to it, please specify them on the" >&2
+        echo "*** '$0' command line." >&2
         echo "" >&2
 fi
 
-set -x
 aclocal --install || exit 1
-autoreconf --verbose --force --install -Wno-portability || exit 1
-{ set +x; } 2>/dev/null
+autoreconf --verbose --force --install || exit 1
 
+cd "$olddir"
 if [ "$NOCONFIGURE" = "" ]; then
-        set -x
         $srcdir/configure "$@" || exit 1
-        { set +x; } 2>/dev/null
 
         if [ "$1" = "--help" ]; then exit 0 else
-                echo "Now type \`make\' to compile $PKG_NAME" || exit 1
+                echo "Now type 'make' to compile $PKG_NAME" || exit 1
         fi
 else
         echo "Skipping configure process."