Sent upstream: https://github.com/hydrogen-music/hydrogen/pull/290

cmake: Call find_path and find_library even if pkg-config calls work.

Instead of calling pkg_check_modules() with the same prefix as the calls

to find_library() and find_path(), pass PC_${prefix} to the former.

This way, we are able to use the paths that might have been found by

pkg-config as hints to the find_library and find_path calls. Doing so

helps systems where the dependent libraries (libarchive, libsndfile etc)

are not in the default linker path, as the linker is now called with the

libraries' absolute path:

c++ file1.o file2.o [...] -o hydrogen /usr/lib/libsndfile.so ...

instead of

c++ file1.o file2.o [...] -o hydrogen -lsndfile ...

as the latter requires one to manually pass "-L/usr/local/lib" to CMake

when configuring Hydrogen.

While here, use HINTS instead of PATHS when calling the find_*()

functions, as CMake's documentation says that "paths computed by system

introspection" should use HINTS, not PATHS, which is for hardcoded

paths.

--- cmake/FindHelper.cmake

+++ cmake/FindHelper.cmake

@@ -23,7 +23,7 @@ macro(FIND_HELPER prefix pkg_name header lib)

             FIND_PACKAGE(PkgConfig)

         endif()

         if(PKG_CONFIG_FOUND)

-            pkg_check_modules(${prefix} ${pkg_name})

+            pkg_check_modules(PC_${prefix} ${pkg_name})

             #MESSAGE(STATUS  " LDFLAGS       ${${prefix}_LDFLAGS}" )

             #MESSAGE(STATUS  " CFLAGS        ${${prefix}_CFLAGS}" )

             #MESSAGE(STATUS  " INCLUDEDIRS   ${${prefix}_INCLUDE_DIRS}" )

@@ -36,12 +36,14 @@ macro(FIND_HELPER prefix pkg_name header lib)

         find_path(${prefix}_INCLUDE_DIR

             NAMES ${header}

-            PATHS ${${prefix}_INCLUDE_DIRS} ${${prefix}_INCLUDEDIR} ${${prefix}_INCLUDE_PATHS} ENV ${prefix}_INCLUDE

+            HINTS ${PC_${prefix}_INCLUDE_DIRS} ${PC_${prefix}_INCLUDEDIR} ${PC_${prefix}_INCLUDE_PATHS}

+            ENV ${prefix}_INCLUDE

         )

         find_library(${prefix}_LIBRARIES

             NAMES ${lib}

-            PATHS ${${prefix}_LIBDIR} ${${prefix}_LIBRARY_DIRS} ${${prefix}_LIB_PATHS} ENV ${prefix}_PATH

+            HINTS ${PC_${prefix}_LIBDIR} ${PC_${prefix}_LIBRARY_DIRS} ${PC_${prefix}_LIB_PATHS}

+            ENV ${prefix}_PATH

         )

     endif()