Fix swiftshader build error

The latest swiftshader needs libxcb-shm headers to build, so install it

Bug: swiftshader:169
Change-Id: I160887765354f1e932b1cabe7d03ab2ac272561a
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/61030
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Tested-by: Peng Huang <penghuang@chromium.org>
Commit-Queue: Peng Huang <penghuang@chromium.org>
diff --git a/tests/kokoro/gcp_ubuntu/continuous.sh b/tests/kokoro/gcp_ubuntu/continuous.sh
index 4f6e86e..bfa5d8d 100755
--- a/tests/kokoro/gcp_ubuntu/continuous.sh
+++ b/tests/kokoro/gcp_ubuntu/continuous.sh
@@ -20,6 +20,9 @@
 sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-9 100 --slave /usr/bin/g++ g++ /usr/bin/g++-9
 sudo update-alternatives --set gcc "/usr/bin/gcc-9"
 
+# Install libxcb-shm0-dev
+sudo aptitude install -yq libxcb-shm0-dev
+
 mkdir -p build && cd build
 
 if [[ -z "${REACTOR_BACKEND}" ]]; then