Fix pkg-config issues for 0.13 #8314

1. 
   theuni commented at 6:39 pm on July 7, 2016: member

   For 0.13, I’d prefer to keep the requirements the same as before: All platforms require pkg-config except for Windows.

   For now, I believe I’ve fixed up the current issues and regressions. Fixes: #8228, replaces #8242.

   Post-0.13, I believe the consensus is to treat Windows like the others and require pkg-config across the board. We can drop all of the non-pkg-config paths, and simply AC_REQUIRE(PKG_PROG_PKG_CONFIG)

2. build: Fix Qt5PlatformSupport check without pkg-config

   The non-pkg-config case can't use pkg-config to check the version.
   
   Also, make sure that the check is properly guarded in the case of missing
   pkg-config macros.

   0c928cb13c
3. build: fix Windows builds without pkg-config

   - guard PKG_PROG_PKG_CONFIG with an m4_ifdef. If not building for windows,
     require it
   - add nops as necessary in case the ifdef reduces the if/then to nothing
   - AC_SUBST some missing _LIBS. These were split out over time, but not all were
     properly substituted. They continued to work if pkg-config is installed
     because it does the AC_SUBST itself

   b556beda26
4. MarcoFalke added this to the milestone 0.13.0 on Jul 7, 2016
5. MarcoFalke added the label Build system on Jul 7, 2016
6. 
   jonasschnelli commented at 6:52 am on July 8, 2016: contributor

   Gitian was happy with this PR: https://bitcoin.jonasschnelli.ch/pulls/8314/
7. 
   laanwj commented at 1:07 pm on July 8, 2016: member

   Works for me - retried #8228 and get an error now, as expected:

   0configure: error: PKG_PROG_PKG_CONFIG macro not found. Please install pkg-config and re-run autogen.sh.
   

8. laanwj merged this on Jul 8, 2016
9. laanwj closed this on Jul 8, 2016

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Contributors
theuni jonasschnelli laanwj

Labels
Build system

Milestone
0.13.0