Add more error printing to know why command buffer lib failed to load.

src/ports/SkOSLibrary_posix.cpp

Index: src/ports/SkOSLibrary_posix.cpp
diff --git a/src/ports/SkOSLibrary_posix.cpp b/src/ports/SkOSLibrary_posix.cpp
index 901ee22f3c942f883c1db2f61d5d953990f7d0d3..6372a8122a18f9f729d373ee06223b12ea16b69f 100644
--- a/src/ports/SkOSLibrary_posix.cpp
+++ b/src/ports/SkOSLibrary_posix.cpp
@@ -12,7 +12,11 @@
 #include <dlfcn.h>
 
 void* DynamicLoadLibrary(const char* libraryName) {
-    return dlopen(libraryName, RTLD_LAZY);
+    void* result = dlopen(libraryName, RTLD_LAZY);
+    if (!result) {
+        SkDebugf("Error loading %s {\n %s\n}\n", libraryName, dlerror());
+    }
+    return result;
 }
 
 void* GetProcedureAddress(void* library, const char* functionName) {