[clang-cache] Handle LLVM_CACHE_PLUGIN_OPTIONS properly for the clang-cache launcher mode

Treat as colon separated options string, that is split to multiple `-fcas-plugin-option` options.

(cherry picked from commit 5c8bc30)

Author: akyrtzi

clang/test/CAS/driver-cache-launcher.c

@@ -38,11 +38,12 @@
 // SPECIFIC-DAEMON-NOT: "-fdepscan-share-identifier"
 // SPECIFIC-DAEMON: "-cc1depscan" "-fdepscan=daemon" "-fdepscan-daemon=[[PREFIX]]/scand"
 
-// RUN: env LLVM_CACHE_CAS_PATH=%t/cas LLVM_CACHE_PLUGIN_PATH=%t/plugin LLVM_CACHE_PLUGIN_OPTIONS=some-opt=value \
+// RUN: env LLVM_CACHE_CAS_PATH=%t/cas LLVM_CACHE_PLUGIN_PATH=%t/plugin LLVM_CACHE_PLUGIN_OPTIONS=some-opt=value:opt2=val2 \
 // RUN:   %clang-cache %clang -c %s -o %t.o -### 2>&1 | FileCheck %s -check-prefix=PLUGIN -DPREFIX=%t
 // PLUGIN: "-fcas-path" "[[PREFIX]]/cas"
 // PLUGIN: "-fcas-plugin-path" "[[PREFIX]]/plugin"
-// PLUGIN: "-fcas-plugin-options" "some-opt=value"
+// PLUGIN: "-fcas-plugin-option" "some-opt=value"
+// PLUGIN: "-fcas-plugin-option" "opt2=val2"
 
 // RUN: env LLVM_CACHE_CAS_PATH=%t/cas LLVM_CACHE_REMOTE_SERVICE_SOCKET_PATH=%t/ccremote %clang-cache %clang -c %s -o %t.o -### 2>&1 | FileCheck %s -check-prefix=REMOTE -DPREFIX=%t
 // REMOTE: "-fcompilation-caching-service-path" "[[PREFIX]]/ccremote"

clang/tools/driver/CacheLauncherMode.cpp

@@ -108,7 +108,12 @@ static void addCommonArgs(bool ForDriver, SmallVectorImpl<const char *> &Args,
   }
   if (auto PluginOpts =
           llvm::sys::Process::GetEnv("LLVM_CACHE_PLUGIN_OPTIONS")) {
-    addCC1Args({"-fcas-plugin-options", Saver.save(*PluginOpts).data()});
+    StringRef Remaining = *PluginOpts;
+    while (!Remaining.empty()) {
+      StringRef Opt;
+      std::tie(Opt, Remaining) = Remaining.split(':');
+      addCC1Args({"-fcas-plugin-option", Saver.save(Opt).data()});
+    }
   }
 }