Empty surface shader throws errors on GLES2 graphics level
Steps to reproduce:
1. Create a new project
2. Create a new shader and make use of it
3. Deploy the project to any device using Open GL ES2.0 graphics level. Upon start error will be thrown:
D/Unity (10112): -------- GLSL error: Fragment shader compilation failed.
D/Unity (10112): ERROR: 0:6: '' : extension 'GL_EXT_draw_buffers' is not supported
D/Unity (10112): ERROR: 0:51: '[' : array index out of range '1'
D/Unity (10112): ERROR: 0:52: '[' : array index out of range '2'
D/Unity (10112): ERROR: 0:53: '[' : array index out of range '3'
D/Unity (10112): ERROR: 4 compilation errors. No code generated.
On GLES 2.0 devices.

GLES 3.0 devices will throw error:
D/Unity ( 8513): -------- GLSL error: Fragment shader compilation failed.
D/Unity ( 8513): ERROR: 0:6: '' : GLSL error: extension 'GL_EXT_draw_buffers' is not supported
D/Unity ( 8513): ERROR: 1 compilation errors. No code generated.
D/Unity ( 8513):
D/Unity ( 8513):
D/Unity ( 8513):
D/Unity ( 8513): Warning: Creation of shader 'Custom/MyShader' failed.