ola: fix compilation of this package

This package does not currently compile.

This is needed to do so that it compiles:
- fix emptying CXX variable in configure script
- fix automake not generating Makefile (remove doxygen definitions)
- force gnu++11 by patch, does not work with configure variable
Also because of changed API in libmicrohttpd:
- fix HttpServer

Moreover this package does not support --disable-slp configure option
anymore, remove it.

Signed-off-by: Marek Behún <kabel@blackhole.sk>

net/ola/Makefile

@@ -55,7 +55,6 @@ CONFIGURE_ARGS += \
 
 HOST_CONFIGURE_ARGS += \
 	--disable-all-plugins \
-	--disable-slp \
 	--disable-osc \
 	--disable-uart \
 	--disable-libusb \
@@ -68,9 +67,6 @@ HOST_CONFIGURE_ARGS += \
 HOST_CPPFLAGS += \
 	-std=gnu++11
 
-CONFIGURE_VARS += \
-	require_gnu_plus_plus_11=yes
-
 HOST_LDFLAGS += -Wl,-rpath$(comma)$(STAGING_DIR_HOSTPKG)/lib
 TARGET_LDFLAGS += $(if $(CONFIG_USE_GLIBC),-lm)