[FGS] curl fgs_build - patch only once`

[Frank Warmerdam]

Folks,

I have committed a change to pkg_def/curl/fgs_build so that the vernum
patch will only be applied once.  Basically, I assume if we have the
patch file in the build directory then it has been applied.

Without this fix doing an "fgsdev build_all" a second time fails on curl.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org