akonadi5: fix cross build

instead of hacking around to get a host protocolgen bin use qemu

srcpkgs/akonadi5/patches/protocolgen-cross.patch

@@ -1,13 +0,0 @@
---- src/private/protocolgen/CMakeLists.txt	2018-01-09 20:34:31.345972552 +0100
-+++ src/private/protocolgen/CMakeLists.txt	2018-01-09 20:45:14.393984830 +0100
-@@ -1,5 +1,10 @@
- project(protocolgen)
- 
-+IF(CMAKE_CROSSCOMPILING)
-+	SET(CMAKE_CXX_COMPILER $ENV{CXX_host})
-+	SET(CMAKE_CXX_FLAGS $ENV{XBPS_CXXFLAGS})
-+ENDIF(CMAKE_CROSSCOMPILING)
-+
- set(protocolgen_SRCS
-     main.cpp
-     cppgenerator.cpp

srcpkgs/akonadi5/template

@@ -4,6 +4,7 @@ version=20.12.2
 revision=1
 wrksrc="akonadi-${version}"
 build_style=cmake
+build_helper="qemu"
 hostmakedepends="extra-cmake-modules qt5-qmake qt5-host-tools python3
  shared-mime-info libxslt pkg-config gettext"
 makedepends="qt5-devel qt5-plugin-mysql qt5-plugin-odbc qt5-plugin-pgsql
@@ -33,17 +34,6 @@ pre_configure() {
 	fi
 }
 
-pre_build() {
-	if [ "$CROSS_BUILD" ]; then
-		sed -e "s?/usr/${XBPS_CROSS_TRIPLET}??g" \
-			-i build/src/private/protocolgen/CMakeFiles/protocolgen.dir/flags.make
-		sed -e "s?/usr/${XBPS_CROSS_TRIPLET}??g" \
-			-i build/src/private/protocolgen/CMakeFiles/protocolgen.dir/link.txt
-		sed -e 's!\&\& protocolgen!\&\& ../../bin/protocolgen!' \
-			-i build/src/private/CMakeFiles/generate_protocol.dir/build.make
-	fi
-}
-
 do_check() {
 	# failing tests are disabled - sqlite tests hang on futex
 	cd build