Implement param capture for glGetUniform calls and extensions

Implement glGetUniform calls to fix crashes in UniformTest test group.

Tests: UniformTest test group
Bug: angleproject:4817
Change-Id: I132c61e053665b0642667aad51f1f3220d101d14
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2339542
Commit-Queue: Manh Nguyen <nguyenmh@google.com>
Reviewed-by: Cody Northrop <cnorthrop@google.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>

src/libANGLE/capture_gles_2_0_params.cpp

@@ -548,7 +548,8 @@ void CaptureGetUniformfv_params(const State &glState,
                                 GLfloat *params,
                                 ParamCapture *paramCapture)
 {
-    UNIMPLEMENTED();
+    // the value returned cannot have size larger than a mat4 of floats
+    paramCapture->readBufferSizeBytes = 64;
 }
 
 void CaptureGetUniformiv_params(const State &glState,
@@ -558,7 +559,8 @@ void CaptureGetUniformiv_params(const State &glState,
                                 GLint *params,
                                 ParamCapture *paramCapture)
 {
-    UNIMPLEMENTED();
+    // the value returned cannot have size larger than a mat4 of ints
+    paramCapture->readBufferSizeBytes = 64;
 }
 
 void CaptureGetVertexAttribPointerv_pointer(const State &glState,

src/libANGLE/capture_gles_ext_params.cpp

@@ -2464,7 +2464,7 @@ void CaptureGetnUniformfvEXT_params(const State &glState,
                                     GLfloat *params,
                                     ParamCapture *paramCapture)
 {
-    UNIMPLEMENTED();
+    paramCapture->readBufferSizeBytes = bufSize;
 }
 
 void CaptureGetnUniformivEXT_params(const State &glState,
@@ -2475,7 +2475,7 @@ void CaptureGetnUniformivEXT_params(const State &glState,
                                     GLint *params,
                                     ParamCapture *paramCapture)
 {
-    UNIMPLEMENTED();
+    paramCapture->readBufferSizeBytes = bufSize;
 }
 
 void CaptureReadnPixelsEXT_data(const State &glState,