OpenGL target not found when linking to garch

[pablode]

Description of Issue

When building an application that links to garch or glf, CMake reports:

-- Configuring done
CMake Error at F:/USD-dev/INSTALL/cmake/pxrTargets.cmake:351 (set_target_properties):
  The link interface of target "garch" contains:

    OpenGL::GL

  but the target was not found.  Possible reasons include:

    * There is a typo in the target name.
    * A find_package call is missing for an IMPORTED target.
    * An ALIAS target is missing.

Call Stack (most recent call first):
  F:/USD-dev/INSTALL/pxrConfig.cmake:77 (include)
  CMakeLists.txt:29 (find_package)

This was most likely introduced by #2827.

Basically, CMake expects an OpenGL::GL target, but there is no find_package(OpenGL REQUIRED) in pxrConfig.cmake.

Steps to Reproduce

System Information (OS, Hardware)

Windows 10

Package Versions

USD dev (should also affect v24.08)

Build Flags

none

[jesschimein]

Filed as internal issue #USD-10178