android: Simplify ldflags processing.

NormalizeLdFlags existed to filter out various linker arguments that
don't belong in the Android build system build, such as including
crtbegin/crtend explicitly in the link. Filtering out flags that happen
to refer to certain paths is mysterious and means you can't refer to
those paths even if you need to; we have instead fixed Chromium's gyp
files to not include these flags in the first place when they aren't
supposed to be there, and removed NormalizeLdFlags entirely.

Similarly, the logic to extract libraries to link from ldflags has been
removed; libraries are now all specified in the normal gyp way under the
"libraries" key.

BUG=
R=mkosiba@chromium.org, sbc@chromium.org

Review URL: https://codereview.chromium.org/14773005

git-svn-id: http://gyp.googlecode.com/svn/trunk@1625 78cadc50-ecff-11dd-a971-7dbc132099af