Handle gaps in FS inputs.

Added logic to handle when user varyings are written by the VS but not read by the FS.
Also moved SBE command building from draw-time to pipeline-create.
diff --git a/icd/common/icd-utils.h b/icd/common/icd-utils.h
index c102158..fdefd16 100644
--- a/icd/common/icd-utils.h
+++ b/icd/common/icd-utils.h
@@ -36,6 +36,7 @@
 #define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
 
 #define u_popcount(u) __builtin_popcount(u)
+#define u_popcountll(u) __builtin_popcountll(u)
 
 #define STATIC_ASSERT(expr) do {            \
     (void) sizeof(char[1 - 2 * !(expr)]);   \