fix bug 3313505
Shader cache cleanup could occur in wrong thread
during RS teardown.

Change-Id: Iffed41de046147db30885e6815826e3b640020c1
diff --git a/rsShaderCache.cpp b/rsShaderCache.cpp
index 45384c9..b958021 100644
--- a/rsShaderCache.cpp
+++ b/rsShaderCache.cpp
@@ -32,10 +32,7 @@
 }
 
 ShaderCache::~ShaderCache() {
-    for (uint32_t ct=0; ct < mEntries.size(); ct++) {
-        glDeleteProgram(mEntries[ct]->program);
-        free(mEntries[ct]);
-    }
+    cleanupAll();
 }
 
 void ShaderCache::updateUniformArrayData(Context *rsc, Program *prog, uint32_t linkedID,
@@ -251,5 +248,10 @@
 }
 
 void ShaderCache::cleanupAll() {
+    for (uint32_t ct=0; ct < mEntries.size(); ct++) {
+        glDeleteProgram(mEntries[ct]->program);
+        free(mEntries[ct]);
+    }
+    mEntries.clear();
 }