measure relinking patch and measured results

measure-relinking.patch

diff --git a/src/mbgl/gl/program.hpp b/src/mbgl/gl/program.hpp
index 3757c442d..9d4eb7c24 100644
--- a/src/mbgl/gl/program.hpp
+++ b/src/mbgl/gl/program.hpp
@@ -23,6 +23,8 @@
 
 #include <string>
 
+#import <QuartzCore/QuartzCore.h>
+
 namespace mbgl {
 namespace gl {
 
@@ -52,8 +54,10 @@ public:
                   context.createShader(ShaderType::Fragment, fragmentSource))),
               attributeLocations(context, program) {
             // Re-link program after manually binding only active attributes in Attributes::queryLocations
+            auto t = CACurrentMediaTime();
             context.linkProgram(program);
-
+            t = (CACurrentMediaTime() - t) * 1000;
+            printf("Relinking took %f ms\n", t);
             // We have to re-initialize the uniforms state from the bindings as the uniform locations
             // get shifted on some implementations
             uniformStates.queryLocations(program);
             
             


Measured, just the relinking, on release build on iPhone SE (A9, same as iPhone 6S)
- 1st run after reboot or installation
Total 37.14ms, average per program:1.86ms

- reopening
Total: 2.47ms, average per program: 0.12ms

reopen   | 1st run on reboot/installation: 
0.089083	1.069083
0.078750	0.507042
0.098250	3.149375
0.100167	3.043375
0.224167	3.108500
0.085375	2.599583
0.132875	0.704458
0.133417	2.531875
0.121333	1.037083
0.118708	1.114417
0.114333	4.230750
0.120625	1.304708
0.105833	2.585708
0.115125	1.305125
0.124333	1.053333
0.113792	3.133375
0.152833	0.894333
0.132708	1.108625
0.155708	1.449792
0.149292	1.214833
	        1.409750
	        3.223042