examples: Link only with ../libusb/libusb-1.0.la and not with -lusb-1.0
examples: Link only with ../libusb/libusb-1.0.la and not with -lusb-1.0

Previous _LDFLAGS included both the freshly built libusb in ../libusb
and -lusb-1.0, where libtool would usually resolve the latter to an
already-installed libusb library in the system. The extra reference
to a second libusb library resulted in failure to build examples on
Mac OS X in some cases, and is plain wrong.

See also the thread at http://marc.info/?m=132637593623667

HounD/libusb-v1.0.19,weizhenwei/libusb,anilgit90/libusb,PersonifyInc/libusbx,tklauser/libusb,daiguangbao/libusb,bra1nb3am3r/libusb,jwrdegoede/libusbx,libusb/libusb,andyvand/libusb,LudovicRousseau/libusbx,CyanogenMod/android_external_libusbx,dasdeepak/libusb,pbatard/libusbx,bert/libusb,byterom/android_external_libusbx,hjelmn/libusb-darwin,dasdeepak/libusb,andyvand/libusb,tonyarkles/libusb,JENETRIC/libusb,HounD/libusb-v1.0.19,araisrobo/libusbx,RealVNC/libusbx,ButterflyNetwork/libusb,leapmotion/libusb,RealVNC/libusbx,libusb/libusb,wuzhenda/libusb,dmitrykos/libusb,legege/libusb,hjelmn/libusbx-temp,ThirdProject/android_external_libusbx,kuldeepdhaka/libusb,dasdeepak/libusb,leapmotion/libusb,philemonf/libusb,pbatard/libusbx-hp,tonyarkles/libusb,ButterflyNetwork/libusb,erhuabushuo/libusb,ashima/libusb,YesVideo/libusb,LightInMotion/libusb,AmesianX/libusb,ndurner/libusbx-suse10,dmitrykos/libusb,erhuabushuo/libusb,avakar/libusbx,hjelmn/libusbx-temp,philemonf/libusb,BuLogics/libusb,libusb/libusb,avakar/libusbx,legege/libusb,ButterflyNetwork/libusb,anilgit90/libusb,LudovicRousseau/libusb,kuldeepdhaka/libusb,Distrotech/libusb,ndurner/libusbx-suse10,ndurner/libusbx-suse10,ThirdProject/android_external_libusbx,bra1nb3am3r/libusb,ButterflyNetwork/libusb,JENETRIC/libusb,bra1nb3am3r/libusb,daiguangbao/libusb,SimplyComplexCo/libusb,ButterflyNetwork/libusb,PAC-ROM/android_external_libusbx,LudovicRousseau/libusbx,tenderlove/libusb,TeamExodus/external_libusbx,AmesianX/libusb,hjelmn/libusbx-temp,PersonifyInc/libusbx,hjelmn/libusb-darwin,SpecLad/libusb-android,erhuabushuo/libusb,BuLogics/libusb,ThirdProject/android_external_libusbx,dmitrykos/libusb,ashima/libusb,pbatard/libusbx-hp,SpecLad/libusb-android,HounD/libusb-v1.0.19,ashima/libusb,CyanogenMod/android_external_libusbx,Distrotech/libusb,TeamExodus/external_libusbx,araisrobo/libusbx,mojca/libusb_pico,tonyarkles/libusb,tklauser/libusb,bert/libusb,legege/libusb,DirtyUnicorns/android_external_libusbx,andyvand/libusb,SimplyComplexCo/libusb,Distrotech/libusb,weizhenwei/libusb,LudovicRousseau/libusbx,YesVideo/libusb,pbatard/libusbx-hp,CyanogenMod/android_external_libusbx,wuzhenda/libusb,dickens/libusb,araisrobo/libusbx,philemonf/libusb,LudovicRousseau/libusb,wuzhenda/libusb,LudovicRousseau/libusb,DirtyUnicorns/android_external_libusbx,tenderlove/libusb,PAC-ROM/android_external_libusbx,byterom/android_external_libusbx,TeamExodus/external_libusbx,LightInMotion/libusb,daiguangbao/libusb,pbatard/libusbx,dmitrykos/libusb,AmesianX/libusb,philemonf/libusb,tklauser/libusb,SimplyComplexCo/libusb,jwrdegoede/libusbx,SpecLad/libusb-android,byterom/android_external_libusbx,PAC-ROM/android_external_libusbx,DirtyUnicorns/android_external_libusbx,YesVideo/libusb,weizhenwei/libusb,kuldeepdhaka/libusb,dickens/libusb,BuLogics/libusb,dickens/libusb,PersonifyInc/libusbx,jwrdegoede/libusbx,leapmotion/libusb,anilgit90/libusb,JENETRIC/libusb,mojca/libusb_pico