pass "-lm" through "LDFLAGS"

wasm2c/examples/callback/Makefile

@@ -1,13 +1,14 @@
 # Use implicit rules for compiling C files.
 CFLAGS=-I../..
+LDFLAGS=-lm
 
 all: callback
 
 clean:
  rm -rf callback callback.wasm callback.c callback.h *.o
 
 callback: main.o callback.o ../../wasm-rt-impl.o ../../wasm-rt-mem-impl.o
- $(CC) $(LDFLAGS) -o $@ $^ -lm
+ $(CC) -o $@ $^ $(LDFLAGS)
 
 callback.wasm: callback.wat ../../../bin/wat2wasm
  ../../../bin/wat2wasm --debug-names $< -o $@

wasm2c/examples/fac/Makefile

@@ -1,13 +1,14 @@
 # Use implicit rules for compiling C files.
 CFLAGS=-I../..
+LDFLAGS=-lm
 
 all: fac
 
 clean:
  rm -rf fac fac.wasm fac.c *.o
 
 fac: main.o fac.o ../../wasm-rt-impl.o
- $(CC) $(LDFLAGS) -o $@ $^ -lm
+ $(CC) -o $@ $^ $(LDFLAGS)
 
 fac.wasm: fac.wat ../../../bin/wat2wasm
  ../../../bin/wat2wasm $< -o $@

wasm2c/examples/rot13/Makefile

@@ -1,13 +1,14 @@
 # Use implicit rules for compiling C files.
 CFLAGS=-I../..
+LDFLAGS=-lm
 
 all: rot13
 
 clean:
  rm -rf rot13 rot13.wasm rot13.c rot13.h *.o
 
 rot13: main.o rot13.o ../../wasm-rt-impl.o ../../wasm-rt-mem-impl.o
- $(CC) $(LDFLAGS) -o $@ $^ -lm
+ $(CC) -o $@ $^ $(LDFLAGS)
 
 main.o: rot13.h
 

wasm2c/examples/threads/Makefile

@@ -1,14 +1,14 @@
 #SANITIZERS=-fsanitize=address -fsanitize=undefined -fno-sanitize-recover=all
 CFLAGS=-I../.. -g -O2 -Wall -Wextra -Wno-unused -Wno-unused-parameter -Wno-array-bounds -Wno-ignored-optimization-argument -Wno-tautological-constant-out-of-range-compare -Wno-infinite-recursion -fno-optimize-sibling-calls -frounding-math -fsignaling-nans ${SANITIZERS} -pthread
-LDFLAGS=${SANITIZERS} -pthread
+LDFLAGS=${SANITIZERS} -pthread -lm
 
 all: threads
 
 clean:
  rm -rf threads sample.wasm sample.c sample.h *.o ../../*.o
 
 threads: threads.o sample.o ../../wasm-rt-impl.o ../../wasm-rt-exceptions-impl.o
- $(CC) $(LDFLAGS) -o $@ $^ -lm
+ $(CC) -o $@ $^ $(LDFLAGS)
 
 sample.wasm: sample.wat ../../../bin/wat2wasm
  ../../../bin/wat2wasm --debug-names $< -o $@