dmalloc defines its own prototypes of alloc/string-functions,
when compiling however with optimizations libc might turn 'strdup' into a macro which can't be overloaded that way anymore.
'undef strdup' before (re)defining.
gcc error: dmalloc.h:460:7: error: expected identifier or '(' before '__extension__'
git-svn-id: svn://svn.openwrt.org/openwrt/packages@31253 3c298f89-4303-0410-b956-a3cf2f4a3e73
