Arch Linux

Description:
trying to include `glm` in a project using CMake:
```cmake
find_package(glm REQUIRED)
```
results in the following error:
```
CMake Error at /lib64/cmake/glm/glmConfig.cmake:10 (message):
File or directory //include referenced by variable GLM_INCLUDE_DIRS does
not exist !
Call Stack (most recent call first):
/lib64/cmake/glm/glmConfig.cmake:16 (set_and_check)
CMakeLists.txt:4 (find_package)
```

Additional info:
* glm-0.9.9.5-1

Steps to reproduce:
```
sudo pacman -S glm
mkdir -p testsource/.cmake
cd testsource/.cmake
rm -rf * # remove cmake cached files
echo 'cmake_minimum_required(VERSION 3.14)
project("Pet project" VERSION 0.0.1 LANGUAGES CXX)
find_package(glm REQUIRED)' > ../CMakeLists.txt
cmake .. # Note: No error here

# CLion's PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl
# Next line is important to reproduce:
PATH=/sbin:${PATH}
rm -rf * # remove cmake cached files
cmake ..
```

output
```
-- The CXX compiler identification is GNU 9.1.0
-- Check for working CXX compiler: /sbin/c++
-- Check for working CXX compiler: /sbin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Error at /lib64/cmake/glm/glmConfig.cmake:10 (message):
File or directory //include referenced by variable GLM_INCLUDE_DIRS does
not exist !
Call Stack (most recent call first):
/lib64/cmake/glm/glmConfig.cmake:16 (set_and_check)
CMakeLists.txt:3 (find_package)


-- Configuring incomplete, errors occurred!
See also "/home/user/testsource/.cmake/CMakeFiles/CMakeOutput.log".
```