contrib: New clang patch for install_db4

Replace the clang patch with a new and improved version that also fixes
the build issues with OpenBSD and FreeBSD's clang, and apply it
unconditionally.

This needs testing on OSX.

contrib/install_db4.sh

@@ -60,15 +60,11 @@ http_get "${BDB_URL}" "${BDB_VERSION}.tar.gz" "${BDB_HASH}"
 tar -xzvf ${BDB_VERSION}.tar.gz -C "$BDB_PREFIX"
 cd "${BDB_PREFIX}/${BDB_VERSION}/"
 
-# Apply a patch when building on OS X to make the build work with Xcode.
-#
-if [ "$(uname)" = "Darwin" ]; then
-  BDB_OSX_ATOMIC_PATCH_URL='https://raw.githubusercontent.com/narkoleptik/os-x-berkeleydb-patch/0007e2846ae3fc9757849f5277018f4179ad17ef/atomic.patch'
-  BDB_OSX_ATOMIC_PATCH_HASH='ba0e2b4f53e9cb0ec58f60a979b53b8567b4565f0384886196f1fc1ef111d151'
-
-  http_get "${BDB_OSX_ATOMIC_PATCH_URL}" atomic.patch "${BDB_OSX_ATOMIC_PATCH_HASH}"
-  patch -p1 < atomic.patch
-fi
+# Apply a patch necessary when building with clang and c++11 (see https://community.oracle.com/thread/3952592)
+CLANG_CXX11_PATCH_URL='https://gist.githubusercontent.com/LnL7/5153b251fd525fe15de69b67e63a6075/raw/7778e9364679093a32dec2908656738e16b6bdcb/clang.patch'
+CLANG_CXX11_PATCH_HASH='7a9a47b03fd5fb93a16ef42235fa9512db9b0829cfc3bdf90edd3ec1f44d637c'
+http_get "${CLANG_CXX11_PATCH_URL}" clang.patch "${CLANG_CXX11_PATCH_HASH}"
+patch -p2 < clang.patch
 
 cd build_unix/