Rework the build system to be more modular

Split most of the work off into make/base.mk and allow for easy wrappers
to be created around that that can build with different instrumentation
in their own build directory.

Create wrappers for the following:
 - release build
 - debug build
 - afl++ fuzzing build
 - static analysis with clang
 - clang memory sanitizer
 - clang address/undefined sanitizer

make/base.mk

@@ -0,0 +1,27 @@
+.PHONY: all clean
+
+CC?=clang
+LD?=clang
+CFLAGS?=-Wall -Wextra -Wpedantic -O0 -g3 -std=c23 -fno-omit-frame-pointer -fno-optimize-sibling-calls -D_POSIX_C_SOURCE=200809L
+LDFLAGS?=
+BUILD_DIR?=build/debug/
+
+SOURCES?=$(shell find src/ -type f -name '*.c')
+OBJECTS=$(patsubst %.c,$(BUILD_DIR)%.o,$(SOURCES))
+DEPENDENCIES=$(OBJECTS:.o=.d)
+TARGET?=oas
+
+all: $(BUILD_DIR)$(TARGET)
+	
+
+$(BUILD_DIR)$(TARGET): $(OBJECTS)
+	$(LD) $(LDFLAGS) -o $@ $^
+
+$(BUILD_DIR)%.o: %.c
+	mkdir -p $(dir $@)
+	$(CC) $(CFLAGS) -MMD -MP -c $< -o $@
+
+-include $(DEPENDENCIES)
+
+clean:
+	rm -rf $(BUILD_DIR)