PKG_CHECK_MODULES: Check if $pkg_cv_[]$1[]_LIBS works

[Alan Modra]

On Tue, Jul 28, 2020 at 11:09:02PM +0930, Alan Modra wrote:
> git commit d70f978b44aafc broke binutils builds on Ubuntu 18.04.4
> 
> dwarf.c:36:10: fatal error: elfutils/debuginfod.h: No such file or directory

configure:12396: checking whether to use debuginfod
configure:12398: result: auto
configure:12404: checking for libdebuginfod >= 0.179
configure:12411: $PKG_CONFIG --exists --print-errors "libdebuginfod >= 0.179"
Package libdebuginfod was not found in the pkg-config search path.
Perhaps you should add the directory containing `libdebuginfod.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libdebuginfod' found
configure:12414: $? = 1
configure:12428: $PKG_CONFIG --exists --print-errors "libdebuginfod >= 0.179"
Package libdebuginfod was not found in the pkg-config search path.
Perhaps you should add the directory containing `libdebuginfod.pc'
to the PKG_CONFIG_PATH environment variable
No package 'libdebuginfod' found
configure:12431: $? = 1
configure:12455: gcc -o conftest -g -Og     conftest.c -ldl  >&5
configure:12455: $? = 0
configure:12501: result: yes

-- 
Alan Modra
Australia Development Lab, IBM