Conditionally install libinput based on availability

libinput is not available on Trusty.

BUG=1034916
R=friedman

Change-Id: Ic408cb7b2a1c28e6d4fec10e1c4b4a50c9c8b414
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1980904
Commit-Queue: Thomas Anderson <thomasanderson@chromium.org>
Commit-Queue: Elliott Friedman <friedman@chromium.org>
Auto-Submit: Thomas Anderson <thomasanderson@chromium.org>
Reviewed-by: Elliott Friedman <friedman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#727203}

build/install-build-deps.sh

@@ -177,7 +177,6 @@ dev_list="\
   libglib2.0-dev
   libglu1-mesa-dev
   libgtk-3-dev
-  libinput-dev
   libkrb5-dev
   libnspr4-dev
   libnss3-dev
@@ -249,7 +248,6 @@ common_lib_list="\
   libgbm1
   libglib2.0-0
   libgtk-3-0
-  libinput10
   libpam0g
   libpango1.0-0
   libpci3
@@ -518,6 +516,12 @@ fi
 if package_exists libvulkan1; then
   lib_list="${lib_list} libvulkan1"
 fi
+if package_exists libinput10; then
+  lib_list="${lib_list} libinput10"
+fi
+if package_exists libinput-dev; then
+  dev_list="${dev_list} libinput-dev"
+fi
 
 # Cross-toolchain strip is needed for building the sysroots.
 if package_exists binutils-arm-linux-gnueabihf; then