[rs] Add nonuniformEXT qualifier in examples/texture-arrays

This fixes corruption of output on some AMD GPUs.

wgpu/examples/texture-arrays/non-uniform.frag

@@ -3,7 +3,7 @@
 #extension GL_EXT_nonuniform_qualifier : require
 
 layout(location = 0) in vec2 v_TexCoord;
-layout(location = 1) flat in int v_Index;  // dynamically non-uniform
+layout(location = 1) nonuniformEXT flat in int v_Index;  // dynamically non-uniform
 layout(location = 0) out vec4 o_Color;
 
 layout(set = 0, binding = 0) uniform texture2D u_Textures[2];

wgpu/examples/texture-arrays/unsized-non-uniform.frag

@@ -3,7 +3,7 @@
 #extension GL_EXT_nonuniform_qualifier : require
 
 layout(location = 0) in vec2 v_TexCoord;
-layout(location = 1) flat in int v_Index;  // dynamically non-uniform
+layout(location = 1) nonuniformEXT flat in int v_Index;  // dynamically non-uniform
 layout(location = 0) out vec4 o_Color;
 
 layout(set = 0, binding = 0) uniform texture2D u_Textures[];