Unbreak Clang 6 build.

databases/libodbc++/files/patch-src-datetime.cpp

@@ -0,0 +1,11 @@
+--- src/datetime.cpp.orig	2018-01-26 22:55:42.426793000 +0000
++++ src/datetime.cpp	2018-01-26 22:56:08.411257000 +0000
+@@ -272,7 +272,7 @@
+ # endif
+ #endif
+       ,ODBCXX_STRING_CONST("%09d"),nanos_);
+-      buf[9] = NULL;// Terminate string
++      buf[9] = '\0';// Terminate string
+     ret+=ODBCXX_STRING(buf);
+   }
+   return ret;