RHEL 9.4 does not have the PKG_CONFIG_PATH environment variable configured even though pkg-config is installed. Therefore, cargo cannot build pango-sys because the pango.pc file is needed. Setting the PKG_CONFIG_PATH environment variable to /usr/lib64/pkgconfig still does not work, even though pango.pc file is in that directory.

PKG_CONFIG_PATH environment variable was to /usr/lib64/pkgconfig because the pango.pc file is in that directory. However, cargo run still says that it cannot find the pango.pc file, even though it now recognizes the PKG_CONFIG_PATH environment variable is pointed to the correct location.