configure.ac: don't always try to add local lib/include paths

Only add them if --prefix= wasn't specified, and only allow
one path of each to be added.  This way Fink and Darwinports
users won't have libs from *both* (which would conflict).

Testing from OSX (Fink and/or Darwinports) users would be greatly
appreciated, as would testers from other non-GNU/Linux systems.

git-svn-id: https://svn.musicpd.org/mpd/trunk@4432 09075e82-0dd4-0310-85a5-a0d7c8717e4f

configure.ac

@@ -23,11 +23,12 @@ case "$CC" in
 	;;
 esac
 
+if test -z "$prefix" || test "x$prefix" = xNONE; then
 	local_lib=
 	local_include=
 
-# aren't autotools supposed to be smart enough to figure this out?
-# oh well, the git-core Makefile managed to do some of the work for us :)
+	# aren't autotools supposed to be smart enough to figure this out?  oh
+	# well, the git-core Makefile managed to do some of the work for us :)
 	case "$host_os" in
 	darwin*)
 		local_lib='/sw/lib /opt/local/lib'
@@ -45,11 +46,18 @@ netbsd*)
 	esac
 
 	for d in $local_lib; do
-	test -d "$d" && LDFLAGS="$LDFLAGS -L$d"
+		if test -d "$d"; then
+			LDFLAGS="$LDFLAGS -L$d"
+			break
+		fi
 	done
 	for d in $local_include; do
-	test -d "$d" && CFLAGS="$CFLAGS -I$d"
+		if test -d "$d"; then
+			CFLAGS="$CFLAGS -I$d"
+			break
+		fi
 	done
+fi
 
 AC_ARG_ENABLE(ao,[  --enable-ao             enable support for libao (default: disable)],[enable_ao=$enableval],[enable_ao=no])
 AC_ARG_ENABLE(shout,[  --disable-shout         disable support for streaming through shout (default: enable)],[enable_shout=$enableval],[enable_shout=yes])