Remove root Makefile that wraps cmake

* linux compilation must now happen with cmake, which can be done in a
  couple of one-liners.

Makefile

@@ -1,13 +0,0 @@
-SRC_DIR := $(shell pwd)
-DST_DIR := $(SRC_DIR)/build
-CMAKE_PARAMS :=
-
-.PHONY: all clean
-
-all: renderdoc
-	@mkdir -p "$(DST_DIR)" && cd "$(DST_DIR)" && \
-		cmake $(CMAKE_PARAMS) "$(SRC_DIR)" && \
-		$(MAKE)
-
-clean:
-	@rm -rf "$(DST_DIR)" bin