eclipse-paho#275 Keep -static suffix for Paho C on Windows

Author: fpagliughi

cmake/FindPahoMqttC.cmake

@@ -5,10 +5,13 @@ if(PAHO_WITH_SSL)
 else()
     set(_PAHO_MQTT_C_LIB_NAME paho-mqtt3a)
 endif()
-# add suffix when using static Paho MQTT C library variant
-#if(PAHO_BUILD_STATIC)
-#    set(_PAHO_MQTT_C_LIB_NAME ${_PAHO_MQTT_C_LIB_NAME}-static)
-#endif()
+
+# add suffix when using static Paho MQTT C library variant on Windows
+if(WIN32)
+    if(PAHO_BUILD_STATIC)
+        set(_PAHO_MQTT_C_LIB_NAME ${_PAHO_MQTT_C_LIB_NAME}-static)
+    endif()
+endif()
 
 find_library(PAHO_MQTT_C_LIBRARIES NAMES ${_PAHO_MQTT_C_LIB_NAME})
 unset(_PAHO_MQTT_C_LIB_NAME)