Steps to reproduce the issue

$ spack install proj build_system=autotools

Error message

1 error found in build log:
     150    checking for SQLITE3... yes
     151    checking for sqlite3... yes
     152    checking for TIFF... yes
     153            found libcurl version 8.0.1
     154    checking for curl_global_init in -lcurl... yes
     155    using external GTest.
  >> 156    checking for GTEST... configure: error: Package requirements (gtest >= 1.8.0) were not met:
     157    
     158    No package 'gtest' found
     159    
     160    Consider adjusting the PKG_CONFIG_PATH environment variable if you
     161    installed software in a non-standard prefix.

Information on your system

• Spack: 0.20.0.dev0 (74ad92e)
• Python: 3.9.2
• Platform: linux-debian11-skylake
• Concretizer: clingo

Additional information

@adamjstewart I don't think that uploading any files is required here (sorry, I have to lie below by setting the corresponding checkbox). It just looks like the configure script fails if GTest is not available, which is the case because googletest is a test dependency.

General information

• I have run spack debug report and reported the version of Spack/Python/Platform
• I have run spack maintainers <name-of-the-package> and @mentioned any maintainers
• I have uploaded the build log and environment files
• I have searched the issues of this repo and believe this is not a duplicate