GLES1: Entry points for lighting and materials

- glLight*/glMaterial and their queries
- Use new packed enums in these entry points, except for lightmodel
which stays GLenum to be consistent with other generic glGet's
- State.cpp: New glGet* queries related to light model and
light/normal rescale enablement
- GLES1State.cpp: Functions to get/set lighting/material state
- Validation for lighting/materials

+ Add a few convenience methods to random_utils for sampling
non-negative floats and a sampler for random booleans

BUG=angleproject:2306

Change-Id: If7ba0c0a0dc75f88fbaa986b904f1ea96ee6512e
Reviewed-on: https://chromium-review.googlesource.com/1065502
Commit-Queue: Lingfeng Yang <lfy@google.com>
Reviewed-by: Geoff Lang <geofflang@chromium.org>

util/random_utils.cpp

@@ -37,6 +37,12 @@ void RNG::reseed(unsigned int newSeed)
     mGenerator.seed(newSeed);
 }
 
+bool RNG::randomBool(float probTrue)
+{
+    std::bernoulli_distribution dist(probTrue);
+    return dist(mGenerator);
+}
+
 int RNG::randomInt()
 {
     std::uniform_int_distribution<int> intDistribution;
@@ -67,6 +73,13 @@ float RNG::randomFloatBetween(float min, float max)
     return floatDistribution(mGenerator);
 }
 
+float RNG::randomFloatNonnegative()
+{
+    std::uniform_real_distribution<float> floatDistribution(0.0f,
+                                                            std::numeric_limits<float>::max());
+    return floatDistribution(mGenerator);
+}
+
 float RNG::randomNegativeOneToOne()
 {
     return randomFloatBetween(-1.0f, 1.0f);