build: run docker with SYS_PTRACE capability

Debug tests need to launch dlv and that needs ptrace.
SYS_PTRACE is not in the default capability list so, add it.
https://docs.docker.com/engine/reference/run/

Change-Id: I3c53e0dd956b731726c5bbf7853d3f30d258dd26
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/287712
Trust: Hyang-Ah Hana Kim <hyangah@gmail.com>
Run-TryBot: Hyang-Ah Hana Kim <hyangah@gmail.com>
Reviewed-by: Robert Findley <rfindley@google.com>
TryBot-Result: kokoro <noreply+kokoro@google.com>
diff --git a/build/all.bash b/build/all.bash
index afd0706..2a83163 100755
--- a/build/all.bash
+++ b/build/all.bash
@@ -60,7 +60,8 @@
 run_test_in_docker() {
   echo "**** Building the docker image ***"
   docker build -t vscode-test-env -f ./build/Dockerfile .
-  docker run --workdir=/workspace -v "$(pwd):/workspace" vscode-test-env ci
+  # For debug tests, we need ptrace.
+  docker run --cap-add SYS_PTRACE --workdir=/workspace -v "$(pwd):/workspace" vscode-test-env ci
 }
 
 prepare_nightly() {