Without that patch the build rule including the input component depends
on other options being enabled, such as e.g. GUI support.
Since our host build is headless and we only need the input component
which actually does not have any such dependencies, we patch to force-
build it.
input component being present is a requirement for e.g. qt5tools
building certain host tools - such as 'kmap2qmap'.
--- /dev/null
+--- ./src/platformsupport/platformsupport.pro 2020-05-11 08:15:08.000000000 +0000
++++ ./src/platformsupport/platformsupport.pro.mod 2020-06-11 21:15:01.922331522 +0000
+@@ -6,13 +6,13 @@
+ eventdispatchers \
+ devicediscovery \
+ fbconvenience \
+- themes
++ themes \
++ input
+
+ qtConfig(freetype)|darwin|win32: \
+ SUBDIRS += fontdatabases
+
+ qtConfig(evdev)|qtConfig(tslib)|qtConfig(libinput)|qtConfig(integrityhid)|qtConfig(xkbcommon) {
+- SUBDIRS += input
+ input.depends += devicediscovery
+ }