Fixed the legacy build system

git-svn-id: https://svn.pjsip.org/repos/pjproject/branches/split-3rd-party@1202 74dad513-b988-da41-8d7b-12977e46ad98
diff --git a/third_party/build/portaudio/os-linux.mak b/third_party/build/portaudio/os-linux.mak
new file mode 100644
index 0000000..508948d
--- /dev/null
+++ b/third_party/build/portaudio/os-linux.mak
@@ -0,0 +1,34 @@
+# @configure_input@
+
+# Define the desired sound device backend
+# Valid values are:
+#   - pa_unix:	    	PortAudio on Unix (OSS or ALSA)
+#   - pa_darwinos:  	PortAudio on MacOSX (CoreAudio)
+#   - pa_old_darwinos:  PortAudio on MacOSX (old CoreAudio, for OSX 10.2)
+#   - pa_win32:	    	PortAudio on Win32 (WMME)
+#
+# There are other values below, but these are handled by PJMEDIA's Makefile
+#   - ds:	    	Win32 DirectSound (dsound.c)
+#   - null:	    	Null sound device (nullsound.c)
+AC_PJMEDIA_SND=pa_unix
+
+# For Unix, specify if ALSA should be supported
+AC_PA_USE_ALSA=0
+
+#
+# PortAudio on Unix
+#
+ifeq ($(AC_PJMEDIA_SND),pa_unix)
+# Host APIs and utils
+export PORTAUDIO_OBJS += pa_unix_hostapis.o pa_unix_util.o
+
+# Include ALSA?
+ifeq ($(AC_PA_USE_ALSA),1)
+export CFLAGS += -DPA_USE_ALSA=1
+export PORTAUDIO_OBJS += pa_linux_alsa.o
+endif
+
+export CFLAGS += -DPA_USE_OSS=1 -DHAVE_SYS_SOUNDCARD_H
+export PORTAUDIO_OBJS += pa_unix_oss.o
+endif
+