[tint] Add DEPS & build support for jsoncpp, langsvr

These are the two dependencies of tintd - the WGSL language server.

Bug: tint:2127
Change-Id: I2f2631d799f8ce8472ec9822ea45b6e4571a7a08
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/174880
Kokoro: Ben Clayton <bclayton@google.com>
Kokoro: Kokoro <noreply+kokoro@google.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Ben Clayton <bclayton@google.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 1a3980d..c9e7c06 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -240,6 +240,9 @@
 option_if_not_defined(TINT_BUILD_TESTS "Build tests" ON)
 option_if_not_defined(TINT_BUILD_AS_OTHER_OS "Override OS detection to force building of *_other.cc files" OFF)
 
+option_if_not_defined(TINT_BUILD_TINTD "Build the WGSL language server" OFF)
+option_if_not_defined(TINT_INSTALL_TINTD "Install the WGSL language server" OFF)
+
 set_if_not_defined(TINT_EXTERNAL_BENCHMARK_CORPUS_DIR "" "Directory that holds a corpus of external shaders to benchmark.")
 
 option_if_not_defined(TINT_ENABLE_BREAK_IN_DEBUGGER "Enable tint::debugger::Break()" OFF)