fix(compiler): Makefile: Do not let target 'build' depend on directory

The target `build` creates a build directory with the same name and
initializes through an invocation of CMake. Regardless of the success
or failure of the CMake invocation, all subsequent invocations of the
target do not invoke CMake anymore, as the target's prerequisites are
satisfied through the existence of the build directory created upon
the first invocation.

This patch changes the dependencies to the build directory with an
intermediate target that depends on a stamp file that is only created
when the first CMake invocation in the build directory succeeds.

compiler/Makefile

@@ -2,7 +2,7 @@ BUILD_DIR=./build
 Python3_EXECUTABLE=
 
 
-build:
+$(BUILD_DIR)/configured.stamp:
 	cmake -B $(BUILD_DIR) -GNinja ../llvm-project/llvm/ \
 	-DLLVM_ENABLE_PROJECTS=mlir \
 	-DLLVM_BUILD_EXAMPLES=OFF \
@@ -15,14 +15,17 @@ build:
 	-DLLVM_EXTERNAL_PROJECTS=zamalang \
 	-DLLVM_EXTERNAL_ZAMALANG_SOURCE_DIR=. \
 	-DPython3_EXECUTABLE=${Python3_EXECUTABLE}
+	touch $@
 
-build-end-to-end-jit: build
+build-initialized: $(BUILD_DIR)/configured.stamp
+
+build-end-to-end-jit: build-initialized
 	cmake --build $(BUILD_DIR) --target end_to_end_jit_test
 
-zamacompiler: build
+zamacompiler: build-initialized
 	cmake --build $(BUILD_DIR) --target zamacompiler
 
-python-bindings: build
+python-bindings: build-initialized
 	cmake --build $(BUILD_DIR) --target ZamalangMLIRPythonModules ZamalangPythonModules
 
 test-check: zamacompiler file-check not