poco:add package for the Poco C++ library

POrtable COmponents is a Modern, powerful open source C++ class libraries
for building network- and internet-based applications that run on desktop,
 server, mobile and embedded systems.

Original Makefile -->
https://dev.openwrt.org/browser/packages/libs/poco/Makefile

add license
add maintainer
update URL to latest github stable version (1.7.0)
change patch to the configure file
add a patch to build with musl-libc

Signed-off-by: Jean-Michel Julien <jean-michel.julien@trilliantinc.com>

libs/poco/patches/100-configure.patch

@@ -0,0 +1,15 @@
+--- a/configure
++++ b/configure
+@@ -231,9 +231,9 @@
+		;;
+
+	*)
+-		showhelp
+-		exit 1
+-		;;
++#		showhelp
++#		exit 1
++#		;;
+	esac
+
+ 	shift

libs/poco/patches/200-strerror.patch

@@ -0,0 +1,11 @@
+--- a/Foundation/src/Error.cpp
++++ b/Foundation/src/Error.cpp
+@@ -66,7 +66,7 @@
+		   without -D_GNU_SOURCE is needed, otherwise the GNU version is
+		   preferred.
+		*/
+-#if defined _GNU_SOURCE && !POCO_ANDROID
++#if (defined _GNU_SOURCE && (defined __GLIBC__ || defined __UCLIBC__)) && !POCO_ANDROID
+		char errmsg[256] = "";
+		return std::string(strerror_r(errorCode, errmsg, 256));
+ #elif (_XOPEN_SOURCE >= 600) || POCO_ANDROID