complie error for openwrt(master 20160921) to resolve these problems

[fzglxyc]

@hubaiz @bmedicke @tajson @dmpop I'm try to complie ddserver for openwrt(tl-mr12u) ,found these error

undefined reference to symbol '_Unwind_Resume@@GCC_3.0'
libgcc_s.so.1:error adding symbols: DSO missing from command line

## Resolve

1. change to "DslrDashboardServer" path
2. edit "Makefile" line 18
   from
   DEPENDS:=+libusb-1.0 +uclibcxx
   change to
   DEPENDS:=+libusb-1.0 +uclibcxx +libstdcpp

3)edit "Makefile" line 34
from
LIBS="-nodefaultlibs -lgcc -lc -lusb-1.0 -lpthread -luClibc++"
change to
LIBS="-lgcc -lc -lusb-1.0 -lpthread -luClibc++"

4)to reconfigury openwrt
make menuconfig
to save config

5. to recomplie ddserver to success