fix: correct library linking order in Makefile

Move -lnetsnmp to end of link command (after source files).
In GCC/Clang, library flags must come after the object files that
reference them for proper symbol resolution.

This fixes 'undefined symbol: init_snmp' runtime errors on Linux.

c_src/Makefile

@@ -10,15 +10,15 @@ UNAME_S := $(shell uname -s)
 CFLAGS = -O3 -std=c99 -fPIC -Wall -Wextra -Wno-unused-parameter
 CFLAGS += -I$(ERL_INCLUDE_PATH)
 
-# Linker flags
-LDFLAGS = -lnetsnmp
+# Libraries (must come after source files in link command)
+LIBS = -lnetsnmp
 
 ifeq ($(UNAME_S),Darwin)
     # macOS specific flags
-    LDFLAGS += -dynamiclib -undefined dynamic_lookup
+    CFLAGS += -dynamiclib -undefined dynamic_lookup
 else
     # Linux flags
-    LDFLAGS += -shared
+    CFLAGS += -shared
 endif
 
 # Target
@@ -31,7 +31,7 @@ all: $(TARGET)
 
 $(TARGET): $(SRC)
 	@mkdir -p ../priv
-	$(CC) $(CFLAGS) $(LDFLAGS) -o $@ $<
+	$(CC) $(CFLAGS) -o $@ $< $(LIBS)
 
 clean:
 	rm -f $(TARGET)