Propagate --strict_system_includes to host options. AFAICT, this was an

oversight when adding the option.

RELNOTES: None.
PiperOrigin-RevId: 352364309

src/main/java/com/google/devtools/build/lib/rules/cpp/CppOptions.java

@@ -1142,6 +1142,7 @@ public FragmentOptions getHost() {
     host.loadCcRulesFromBzl = loadCcRulesFromBzl;
     host.validateTopLevelHeaderInclusions = validateTopLevelHeaderInclusions;
     host.parseHeadersSkippedIfCorrespondingSrcsFound = parseHeadersSkippedIfCorrespondingSrcsFound;
+    host.strictSystemIncludes = strictSystemIncludes;
 
     // Save host options for further use.
     host.hostCoptList = hostCoptList;