Revert “cmake: configure libsecp256k1.pc during install” #1694

1. 
   purpleKarrot commented at 2:53 pm on June 30, 2025: contributor

   This reverts commit 7106dce6fd410043fc297139c6307cb6016d2a7b.

   This causes a regression for packaging, as the generated .pc file will contain the location that was used to build the package archive.

2. Revert "cmake: configure libsecp256k1.pc during install"

   This reverts commit 7106dce6fd410043fc297139c6307cb6016d2a7b.
   
   This causes a regression for packaging, as the generated
   `.pc` file will contain the location that was used to build
   the package archive.

   44b205e9ee
3. real-or-random added the label bug on Jul 1, 2025
4. real-or-random added the label build on Jul 1, 2025
5. 
   real-or-random commented at 7:02 am on July 1, 2025: contributor

   That’s unfortunate, yeah. For anyone else, see @purpleKarrot’s comment in #1692 for more context.
6. real-or-random approved
7. 
   real-or-random commented at 7:02 am on July 1, 2025: contributor

   ACK 44b205e9eeac216a1cd15a910709606aca633947

Contributors
purpleKarrot real-or-random

Labels
bug build