package/paho-mqtt-c: sample file path without white-space

By default sample files are installed to share/doc/Eclipse Paho C/.
The white-space can cause problems later down the line.
Therefore the path is changed to the one used by paho-mqtt-c
when configured to build the .deb package, which is share/doc/libpaho-mqtt.

Before:
Install configuration: "Release"
Installing: $(STAGING_DIR)/usr/share/doc/Eclipse Paho C/MQTTAsync_publish.c
Installing: $(STAGING_DIR)/usr/share/doc/Eclipse Paho C/MQTTAsync_publish_time.c
Installing: $(STAGING_DIR)/usr/share/doc/Eclipse Paho C/MQTTAsync_subscribe.c

After:
Install configuration: "Release"
Installing: $(STAGING_DIR)/usr/share/doc/libpaho-mqtt/MQTTAsync_publish.c
Installing: $(STAGING_DIR)/usr/share/doc/libpaho-mqtt/MQTTAsync_publish_time.c
Installing: $(STAGING_DIR)/usr/share/doc/libpaho-mqtt/MQTTAsync_subscribe.c

Signed-off-by: Daniel Lang <d.lang@abatec.at>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
(cherry picked from commit 51eedcf465581e06db3f487e4581bfc2dc45e326)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/paho-mqtt-c/paho-mqtt-c.mk

@@ -11,6 +11,7 @@ PAHO_MQTT_C_LICENSE_FILES = epl-v20 edl-v10 LICENSE
 PAHO_MQTT_C_INSTALL_STAGING = YES
 
 PAHO_MQTT_C_CONF_OPTS = \
+	-DCMAKE_INSTALL_DOCDIR=share/doc/libpaho-mqtt \
 	-DPAHO_ENABLE_TESTING=FALSE \
 	-DPAHO_ENABLE_CPACK=FALSE \
 	-DPAHO_HIGH_PERFORMANCE=TRUE