Fix poco build to actually use the nix provided dependencies, and fix…

… the static build that broke as fallout from that

pkgs/by-name/po/poco/disable-internal-pcre-files-for-non-static-builds.patch

@@ -0,0 +1,23 @@
+diff --git a/Foundation/CMakeLists.txt b/Foundation/CMakeLists.txt
+index d5f3b267d..dfaf99a10 100644
+--- a/Foundation/CMakeLists.txt
++++ b/Foundation/CMakeLists.txt
+@@ -31,11 +31,13 @@ if(POCO_UNBUNDLED)
+ 	find_package(ZLIB REQUIRED)
+ 	find_package(Utf8Proc REQUIRED)
+
+-	#HACK: Unicode.cpp requires functions from these files. The can't be taken from the library
+-	POCO_SOURCES(SRCS RegExp
+-		src/pcre2_ucd.c
+-		src/pcre2_tables.c
+-	)
++    if(NOT POCO_STATIC AND BUILD_SHARED_LIBS)
++    	#HACK: Unicode.cpp requires functions from these files. The can't be taken from the library
++    	POCO_SOURCES(SRCS RegExp
++    		src/pcre2_ucd.c
++    		src/pcre2_tables.c
++        )
++    endif()
+
+ else()
+ 	# pcre2

pkgs/by-name/po/poco/package.nix

@@ -10,6 +10,7 @@
   sqlite,
   openssl,
   unixODBC,
+  utf8proc,
   libmysqlclient,
 }:
 
@@ -32,6 +33,7 @@ stdenv.mkDerivation rec {
 
   buildInputs = [
     unixODBC
+    utf8proc
     libmysqlclient
   ];
   propagatedBuildInputs = [
@@ -50,8 +52,15 @@ stdenv.mkDerivation rec {
   MYSQL_DIR = libmysqlclient;
   MYSQL_INCLUDE_DIR = "${MYSQL_DIR}/include/mysql";
 
-  configureFlags = [
-    "--unbundled"
+  cmakeFlags = [
+    # use nix provided versions of sqlite, zlib, pcre, expat, ... instead of bundled versions
+    "-DPOCO_UNBUNDLED=ON"
+  ];
+
+  patches = [
+    # poco builds its own version of pcre, disable it
+    # https://github.com/pocoproject/poco/issues/4871
+    ./disable-internal-pcre-files-for-non-static-builds.patch
   ];
 
   postFixup = ''