Add missing preprocessor macro for ESSL (#2298)

Co-authored-by: Christophe Dehais <[email protected]>

tools/shaderc/shaderc.cpp

@@ -1106,6 +1106,7 @@ namespace bgfx
 				preprocessor.setDefine(hlslDefine);
 			}
 			else if (0 != glsl)
+			     || (0 != essl)
 			{
 				preprocessor.setDefine(glslDefine);
 			}
@@ -1127,6 +1128,7 @@ namespace bgfx
 				preprocessor.setDefine(hlslDefine);
 			}
 			else if (0 != glsl)
+			     || (0 != essl)
 			{
 				preprocessor.setDefine(glslDefine);
 			}