Add warning flags to makefile and clean up code to remove warnings

contrib/long_distance_matching/Makefile

@@ -9,6 +9,14 @@
 
 # This Makefile presumes libzstd is installed, using `sudo make install`
 
+CFLAGS  ?= -O3
+DEBUGFLAGS = -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow \
+            -Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement \
+            -Wstrict-prototypes -Wundef -Wpointer-arith -Wformat-security \
+            -Wvla -Wformat=2 -Winit-self -Wfloat-equal -Wwrite-strings \
+            -Wredundant-decls
+CFLAGS  += $(DEBUGFLAGS) $(MOREFLAGS)
+FLAGS    = $(CPPFLAGS) $(CFLAGS)
 
 LDFLAGS += -lzstd
 
@@ -22,7 +30,7 @@ all: main-ldm
 #main : ldm.c main.c
 #	$(CC) $(CPPFLAGS) $(CFLAGS) $^ $(LDFLAGS) -o $@
 
-main-ldm : ldm.c main-ldm.c
+main-ldm : util.c ldm.c main-ldm.c
 	$(CC) $(CPPFLAGS) $(CFLAGS) $^ $(LDFLAGS) -o $@
 
 clean: