Issues with pkgconfig file using spack install for hip

[David Rogers]

Installing magma using cmake/spack for the HIP/ROCM backend creates an invalid magma.pc file:

prefix=/sw/spock/spack-envs/base/opt/cray-sles15-zen2/cce-12.0.1/magma-2.6.1-lygndxbmeayg3nxejyr33cpg6atbtrki
exec_prefix=${prefix}
libdir=${exec_prefix}/lib
includedir=${prefix}/include

Name: magma
Description: Matrix Algebra on GPU and Multicore Architectures
Version: 2.6.1
Cflags: -I${includedir}  -std=c99 -fopenmp -Wall -Wno-unused-function
Libs: -L${libdir} -lmagma_sparse -lmagma  /opt/cray/pe/libsci/21.06.1.1/CRAY/9.0/x86_64/lib/libsci_cray.so hip::device roc::hipblas roc::hipsparse
Libs.private:
Requires: 
Requires.private:

The issue seems to be caused by incomplete substitution of @LIBS from CMakeLists.txt before the call to:

configure_file( "${pkgconfig}.in" "${pkgconfig}" @ONLY )