fix win

src/cc/makecustom

@@ -1,6 +1,7 @@
 #!/bin/sh
-gcc -O3 -DBUILD_CUSTOMCC -std=c++11 -I../secp256k1/include -I../univalue/include -I../cryptoconditions/include -I../cryptoconditions/src -I../cryptoconditions/src/asn -I.. -I. -fPIC -shared -c -o customcc.so cclib.cpp
-cp customcc.so ../libcc.so
-cd ..
-make
-cd cc
+if make -f Makefile_custom "$@"; then
+  echo CUSTOMCC BUILD SUCCESSFUL
+else
+  echo CUSTOMCC BUILD FAILED
+  exit 1
+fi