gitian: make windows build deterministic

contrib/gitian-descriptors/gitian-win.yml

@@ -63,6 +63,30 @@ script: |
         chmod +x ${WRAP_DIR}/${i}-${prog}
     done
   done
+
+  # Create per-host linker wrapper
+  # This is only needed for trusty, as the mingw linker leaks a few bytes of
+  # heap, causing non-determinism. See discussion in https://github.com/bitcoin/bitcoin/pull/6900
+  for i in $HOSTS; do
+    mkdir -p ${WRAP_DIR}/${i}
+    for prog in collect2; do
+        echo '#!/bin/bash' > ${WRAP_DIR}/${i}/${prog}
+        REAL=$(${i}-gcc -print-prog-name=${prog})
+        echo "export MALLOC_PERTURB_=255" >> ${WRAP_DIR}/${i}/${prog}
+        echo "${REAL} \$@" >> $WRAP_DIR/${i}/${prog}
+        chmod +x ${WRAP_DIR}/${i}/${prog}
+    done
+    for prog in gcc g++; do
+        echo '#!/bin/bash' > ${WRAP_DIR}/${i}-${prog}
+        echo "REAL=\`which -a ${i}-${prog} | grep -v ${WRAP_DIR}/${i}-${prog} | head -1\`" >> ${WRAP_DIR}/${i}-${prog}
+        echo 'export LD_PRELOAD=/usr/lib/x86_64-linux-gnu/faketime/libfaketime.so.1' >> ${WRAP_DIR}/${i}-${prog}
+        echo "export FAKETIME=\"${REFERENCE_DATETIME}\"" >> ${WRAP_DIR}/${i}-${prog}
+        echo "export COMPILER_PATH=${WRAP_DIR}/${i}" >> ${WRAP_DIR}/${i}-${prog}
+        echo "\$REAL \$@" >> $WRAP_DIR/${i}-${prog}
+        chmod +x ${WRAP_DIR}/${i}-${prog}
+    done
+  done
+
   export PATH=${WRAP_DIR}:${PATH}
 
   cd bitcoin