Gawain: shrink ShaderInterface name buffer

ShaderInterface stores names of custom uniforms and all attributes in an internal buffer, but it doesn't know how large to make this buffer until all inputs are scanned.

This commit shrinks the buffer to the exact size needed.

intern/gawain/src/shader_interface.c

@@ -192,14 +192,34 @@ ShaderInterface* ShaderInterface_create(GLint program)
 #endif
 		}
 
-	// TODO: realloc shaderface to shrink name buffer
-	//       each input->name will need adjustment (except static built-in names)
+	const uint32_t name_buffer_used = name_buffer_offset;
 
 #if DEBUG_SHADER_INTERFACE
-	printf("using %u of %u bytes from name buffer\n", name_buffer_offset, name_buffer_len);
+	printf("using %u of %u bytes from name buffer\n", name_buffer_used, name_buffer_len);
 	printf("}\n"); // exit function
 #endif
 
+	if (name_buffer_used < name_buffer_len)
+		{
+		// realloc shaderface to shrink name buffer
+		ShaderInterface* orig_pointer = shaderface;
+		shaderface = realloc(shaderface, offsetof(ShaderInterface, inputs) + input_ct * sizeof(ShaderInput) + name_buffer_used);
+		const ptrdiff_t delta = shaderface - orig_pointer;
+
+		if (delta)
+			{
+			// each input->name will need adjustment (except static built-in names)
+			const uint32_t input_ct = shaderface->uniform_ct + shaderface->attrib_ct;
+			for (uint32_t i = 0; i < input_ct; ++i)
+				{
+				ShaderInput* input = shaderface->inputs + i;
+
+				if (input->builtin_type == UNIFORM_CUSTOM || input->builtin_type == UNIFORM_NONE)
+					input->name += delta;
+				}
+			}
+		}
+
 	return shaderface;
 	}