Fix minor GYP error in webrtc/tools/internal_tools.gyp
Fix minor GYP error in webrtc/tools/internal_tools.gyp

It seems 'deps' is similar to 'dependencies' for the ninja and make
generators in GYP, but some generators does not support it.
Better use the correct key.
This was introduced in https://codereview.webrtc.org/1387243002/

TBR=phoglund@webrtc.org

Review URL: https://codereview.webrtc.org/1386353003 .

Cr-Original-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#10200}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: 78543284d0010efa4270ff9c102b673593c4827b

jchavanton/webrtc,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,jchavanton/webrtc,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,aleonliao/webrtc-trunk,aleonliao/webrtc-trunk,jchavanton/webrtc,jchavanton/webrtc,aleonliao/webrtc-trunk,jchavanton/webrtc,Alkalyne/webrtctrunk,aleonliao/webrtc-trunk,Alkalyne/webrtctrunk,aleonliao/webrtc-trunk,jchavanton/webrtc,jchavanton/webrtc,Alkalyne/webrtctrunk,aleonliao/webrtc-trunk