BUILD: Use pkg-config to check for OpenAL Soft

macOS is still using Apple's OpenAL framework.

configure.ac

@@ -191,7 +191,7 @@ dnl Graphic libraries
 AX_CHECK_QT5(5.7.1, , AC_MSG_ERROR([Qt5 (>= 5.7.1, modules Core, Gui, Widgets) is required and could not be found!]))
 
 dnl Sound libraries
-AX_CHECK_AL( , AC_MSG_ERROR([OpenAL or OpenAL Soft (>= 1.12) is required and could not be found!]))
+AX_CHECK_AL([1.12],  , AC_MSG_ERROR([OpenAL Soft (>= 1.12) is required and could not be found!]))
 AX_CHECK_MAD(0, 15, 1, , AC_MSG_ERROR([libMAD (>= 0.15.1) is required and could not be found!]))
 AX_CHECK_OGG(, AC_MSG_ERROR([libOgg (>= 1.2.0) is required and could not be found!]))
 AX_CHECK_VORBIS(, AC_MSG_ERROR([libVorbisFile (>= 1.3.1) is required and could not be found!]))

dists/debian/copyright

@@ -78,7 +78,7 @@ Copyright: 2017 Sven Hesse <[email protected]>
 License: CC0-1.0
 
 Files: m4/ax_check_al.m4
-Copyright: 2013 Sven Hesse <[email protected]>
+Copyright: 2013, 2018 Sven Hesse <[email protected]>
            2013 Matthew Hoops <[email protected]>
 License: CC0-1.0
 

m4/ax_check_al.m4

@@ -1,18 +1,18 @@
-#serial 1000
-dnl @synopsis AX_CHECK_AL(action-if, action-if-not)
+#serial 1001
+dnl @synopsis AX_CHECK_AL(version, action-if, action-if-not)
 dnl
-dnl @summary check for OpenAL Soft.
+dnl @summary check for OpenAL (Soft).
 dnl
 dnl Defines AL_LIBS, AL_CFLAGS.
 dnl
 dnl @category InstalledPackages
 dnl @author Sven Hesse <[email protected]>, Matthew Hoops <[email protected]>
-dnl @version 2013-12-14
+dnl @version 2018-06-19
 dnl @license Creative Commons CC0 1.0 Universal Public Domain Dedication
 
 AC_DEFUN([AX_CHECK_AL], [
-	AC_ARG_VAR(AL_CFLAGS, [C compiler flags for OpenAL Soft])
-	AC_ARG_VAR(AL_LIBS, [libraries to pass to the linker for OpenAL Soft])
+	AC_ARG_VAR(AL_CFLAGS, [C compiler flags for OpenAL (Soft)])
+	AC_ARG_VAR(AL_LIBS, [libraries to pass to the linker for OpenAL (Soft)])
 
 	case "$target" in
 		*darwin*)
@@ -24,39 +24,13 @@ AC_DEFUN([AX_CHECK_AL], [
 			if test -z "$AL_LIBS"; then
 				AL_LIBS="-framework OpenAL"
 			fi
-
-			noal=0
 			;;
 
 		*)
-			if test -z "$AL_CFLAGS"; then
-				AL_CFLAGS=""
-			fi
-			if test -z "$AL_LIBS"; then
-				AL_LIBS="-lopenal"
-			fi
-
-			save_CFLAGS="$CFLAGS"
-			save_CXXFLAGS="$CXXFLAGS"
-			save_LIBS="$LIBS"
-			CFLAGS="$CFLAGS $AL_CFLAGS"
-			CXXFLAGS="$CXXFLAGS $AL_CFLAGS"
-			LIBS="$LIBS $AL_LIBS"
-
-			AC_CHECK_HEADER([AL/al.h], AC_CHECK_HEADER([AL/alc.h], noal=0, noal=1), noal=1)
-
-			CFLAGS="$save_CFLAGS"
-			CXXFLAGS="$save_CXXFLAGS"
-			LIBS="$save_LIBS"
+			PKG_CHECK_MODULES([AL], [openal >= $1], [$2], [$3])
 			;;
 	esac;
 
-	if test "$noal" = "1"; then
-		ifelse([$2], , :, [$2])
-	else
-		ifelse([$1], , :, [$1])
-	fi
-
 	AC_SUBST(AL_CFLAGS)
 	AC_SUBST(AL_LIBS)
 ])