Fix search links when clicking in areas that are not covered by the clang plugin.

Mentioned on https://wiki.mozilla.org/Webtools/DXR_User_Research:
	no, I don't want to search "CGAffineTransform);" complete
	with the close-parent-and-semicolon...
Now we only select things that look like C++ identifiers so the above
would search for "CGAffineTransform" as desired.