Force CMAKE_SKIP_RPATH=ON

Fix empty RPATH token issue. Only affects Linux and FreeBSD.

contrib/gitian/gitian-freebsd.yml

@@ -119,7 +119,7 @@ script: |
   for i in ${HOSTS}; do
     export PATH=${WRAP_DIR}:${BASEPREFIX}/${i}/native/bin:${ORIGPATH}
     mkdir build && cd build
-    cmake .. -DCMAKE_TOOLCHAIN_FILE=${BASEPREFIX}/${i}/share/toolchain.cmake -DCMAKE_BUILD_TYPE=Release
+    cmake .. -DCMAKE_TOOLCHAIN_FILE=${BASEPREFIX}/${i}/share/toolchain.cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_SKIP_RPATH=ON
     make ${MAKEOPTS}
     chmod 755 bin/*
     cp ../LICENSE bin

contrib/gitian/gitian-linux.yml

@@ -164,7 +164,7 @@ script: |
     fi
     export C_INCLUDE_PATH="$EXTRA_INCLUDES"
     export CPLUS_INCLUDE_PATH="$EXTRA_INCLUDES"
-    cmake .. -DCMAKE_TOOLCHAIN_FILE=${BASEPREFIX}/${i}/share/toolchain.cmake -DBACKCOMPAT=ON
+    cmake .. -DCMAKE_TOOLCHAIN_FILE=${BASEPREFIX}/${i}/share/toolchain.cmake -DBACKCOMPAT=ON -DCMAKE_SKIP_RPATH=ON
     make ${MAKEOPTS}
     chmod 755 bin/*
     cp ../LICENSE bin