mapnik: revision for gdal

[iMichka]

• Have you followed the guidelines for contributing?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with brew install --build-from-source <formula>, where <formula> is the name of the formula you're submitting?
• Is your test running fine brew test <formula>, where <formula> is the name of the formula you're submitting?
• Does your build pass brew audit --strict <formula> (after doing brew install <formula>)?

---

Fixes:

2020-11-29T15:40:57.4198860Z �[34m==>�[0m �[1mbrew linkage --test mapnik�[0m
2020-11-29T15:40:59.6497430Z �[31m==>�[0m �[1m�[31mFAILED�[0m�[0m
2020-11-29T15:40:59.6498070Z Missing libraries:
2020-11-29T15:40:59.6498620Z   unexpected (/usr/lib/libpq.5.dylib)
2020-11-29T15:40:59.6499170Z Broken dependencies:
2020-11-29T15:40:59.6499900Z   /usr/local/opt/gdal/lib/libgdal.27.dylib (gdal)

[fxcoudert]

I don't understand where the /usr/lib/libpq.5.dylib is coming from

[iMichka]

gdal depends on libpq. But I am unsure what happened here.

I saw this while rebuilding poppler on CI.

[fxcoudert]

There are some upstream fixes for it, but I don't know which commit is the right one (if any): mapnik/mapnik#4196

[Rylan12]

FYI using @redneb's patch that they linked in mapnik/mapnik#4196 worked locally.

[iMichka]

I asked if they can tag a new release. If not, I'll add the patch tomorrow.

[BrewTestBot]

@iMichka has triggered a merge.

[iMichka]

I went for the patch as the new release should come before end of the year, but we did not get a clear date.