package/poco: fix BR2_SHARED_STATIC_LIBS build

poco can't be built statically since commit
073a89196a22f995c142cd11640d3cfb7cef691d. However, commit
add7c433d250e153d9e58fe7da3bd52171ba2652 enabled static (and shared)
build with BR2_SHARED_STATIC_LIBS resulting in the following build
failure since at least version 1.11.1:

/home/buildroot/autobuild/instance-1/output-1/host/opt/ext-toolchain/bin/../lib/gcc/mips-buildroot-linux-gnu/11.2.0/../../../../mips-buildroot-linux-gnu/bin/ld: /home/buildroot/autobuild/instance-1/output-1/build/poco-1.11.1/lib/Linux/mips/libPocoXML.a(ParserEngine.o): in function `Poco::XML::ParserEngine::handleStartElement(void*, char const*, char const**)':
ParserEngine.cpp:(.text+0x2f8): undefined reference to `XML_GetSpecifiedAttributeCount'

Fixes: add7c433d250e153d9e58fe7da3bd52171ba2652
 - http://autobuild.buildroot.org/results/afc434a13d5e7a8affa4abb4058d7bebc81aca29
 - http://autobuild.buildroot.org/results/860b70a8c9c4a6a53247ac4bdb4fd0851b28c61a

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit fd484c1f57781aed6e99a61cbfae21e0edbe7dd8)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/poco/poco.mk

@@ -57,13 +57,7 @@ ifeq ($(BR2_SOFT_FLOAT),y)
 POCO_CONF_OPTS += --no-fpenvironment
 endif
 
-ifeq ($(BR2_STATIC_LIBS),y)
-POCO_MAKE_TARGET = static_release
-else ifeq ($(BR2_SHARED_LIBS),y)
 POCO_MAKE_TARGET = shared_release
-else ifeq ($(BR2_SHARED_STATIC_LIBS),y)
-POCO_MAKE_TARGET = all_release
-endif
 
 POCO_LDFLAGS=$(TARGET_LDFLAGS)
 ifeq ($(BR2_TOOLCHAIN_HAS_LIBATOMIC),y)