fix typo in c++ header check

Change-Id: Ibb4dd0abe104ea5e6d46c7deb1ef0856e7cfda51
Reviewed-on: https://skia-review.googlesource.com/138991
Auto-Submit: Mike Klein <mtklein@chromium.org>
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
diff --git a/skcms_internal.h b/skcms_internal.h
index d8fe695..3e2fc2b 100644
--- a/skcms_internal.h
+++ b/skcms_internal.h
@@ -14,7 +14,7 @@
 #include <stdbool.h>
 #include <stdint.h>
 
-#if defined(__cpluscplus)
+#ifdef __cplusplus
 extern "C" {
 #endif
 
@@ -46,6 +46,6 @@
     static inline float fabsf_(float x) { return x < 0 ? -x : x; }
     float powf_(float, float);
 
-#if defined(__cpluscplus)
-}  // extern "C"
+#ifdef __cplusplus
+}
 #endif