make yum install optional to future-proof against the Debian-based superchain image

Author: njlynch

buildspec-pr.yaml

@@ -15,7 +15,7 @@ phases:
 
       # Packing the mono-libraries (monocdk & aws-cdk-lib) can cause
       # memory errors. Increasing this value allows our build to more consistently succeed
-      - yum install -y procps-ng && /sbin/sysctl -w vm.max_map_count=2251954
+      - (command -v sysctl || yum install -y procps-ng) && /sbin/sysctl -w vm.max_map_count=2251954
   build:
     commands:
       - /bin/bash ./build.sh --extract