package/speex: add optional dependency to speexdsp

Quoting speex release notes from https://www.speex.org

"Speex 1.2rc2 and SpeexDSP 1.2rc2 are out
 December 6, 2014
 This release splits the speex codec library and the speex DSP library
 into separate source trees."

After bumping speex to 1.2.0 DSP support is provided by speexdsp.

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/speex/speex.mk

@@ -13,6 +13,10 @@ SPEEX_DEPENDENCIES = host-pkgconf libogg
 SPEEX_CONF_OPTS = \
 	--enable-fixed-point
 
+ifeq ($(BR2_PACKAGE_SPEEXDSP),y)
+SPEEX_DEPENDENCIES += speexdsp
+endif
+
 ifeq ($(BR2_PACKAGE_SPEEX_ARM4),y)
 SPEEX_CONF_OPTS += --enable-arm4-asm
 endif