Set the current gamma ramp to original gamma ramp at start.

src/cocoa_init.m

@@ -228,6 +228,7 @@ int _glfwPlatformInit(void)
     // Save the original gamma ramp
     _glfwLibrary.originalRampSize = CGDisplayGammaTableCapacity(CGMainDisplayID());
     _glfwPlatformGetGammaRamp(&_glfwLibrary.originalRamp);
+    _glfwLibrary.currentRamp = _glfwLibrary.originalRamp;
     
     return GL_TRUE;
 }

src/win32_init.c

@@ -163,6 +163,7 @@ int _glfwPlatformInit(void)
     // Save the original gamma ramp
     _glfwLibrary.originalRampSize = 256;
     _glfwPlatformGetGammaRamp(&_glfwLibrary.originalRamp);
+    _glfwLibrary.currentRamp = _glfwLibrary.originalRamp;
 
     _glfwInitTimer();
 

src/x11_init.c

@@ -502,6 +502,7 @@ static void initGammaRamp(void)
 
     // Save the original gamma ramp
     _glfwPlatformGetGammaRamp(&_glfwLibrary.originalRamp);
+    _glfwLibrary.currentRamp = _glfwLibrary.originalRamp;
 }