Initial refactor of shaderbuilder to prepare for geometry shaders

gitignore for eclipse

BUG=skia:
R=bsalomon@google.com, bsalomon@chromium.org

Author: joshualitt@chromium.org

Review URL: https://codereview.chromium.org/491673002
diff --git a/src/core/SkString.cpp b/src/core/SkString.cpp
index 1e29dc7..48459db 100644
--- a/src/core/SkString.cpp
+++ b/src/core/SkString.cpp
@@ -583,6 +583,14 @@
     this->prepend(buffer, strlen(buffer));
 }
 
+void SkString::prependVAList(const char format[], va_list args) {
+    char    buffer[kBufferSize];
+    VSNPRINTF(buffer, kBufferSize, format, args);
+
+    this->prepend(buffer, strlen(buffer));
+}
+
+
 ///////////////////////////////////////////////////////////////////////////////
 
 void SkString::remove(size_t offset, size_t length) {