mark linux-only B-Ds as such

feature enablement/disablement on non-linux arch still needs to be done

debian/control

@@ -11,10 +11,10 @@ Build-Depends: cmake (>= 3.18~),
                libcups2-dev,
                libdbus-1-dev,
                libdouble-conversion-dev,
-               libdrm-dev,
+               libdrm-dev [linux-any],
                libfontconfig-dev,
                libfreetype-dev,
-               libgbm-dev,
+               libgbm-dev [linux-any],
                libgl-dev,
                libgl1-mesa-dev,
                libgles-dev,
@@ -23,23 +23,23 @@ Build-Depends: cmake (>= 3.18~),
                libgtk-3-dev,
                libharfbuzz-dev,
                libicu-dev,
-               libinput-dev,
+               libinput-dev [linux-any],
                libkrb5-dev,
                liblttng-ust-dev,
                libmariadb-dev-compat,
                libmd4c-dev,
                libmd4c-html0-dev,
-               libmtdev-dev,
+               libmtdev-dev [linux-any],
                libpq-dev,
                libproxy-dev,
                libsctp-dev,
                libsqlite3-dev,
                libssl-dev,
-               libsystemd-dev,
+               libsystemd-dev [linux-any],
                libts-dev,
-               libudev-dev,
-               libvulkan-dev,
-               libwayland-dev,
+               libudev-dev [linux-any],
+               libvulkan-dev [linux-any],
+               libwayland-dev [linux-any],
                libx11-dev,
                libx11-xcb-dev,
                libxcb-glx0-dev,