cmake : add config version support (ggml/1582)

* cmake : add config version support (wip) [no ci]

This commit adds support for find_package using a version, for example:
```
find_package(ggml 0.19.0 REQUIRED)
```

examples/test-cmake has been updated to use this and build scripts have
been added to verify this manually. This is still a work in progress and
I'm not sure about the scripts and if we can find better ways to test
this but it might be useful to have for verification of changes to the
cmake build.

* cmake : add semver to ggml backends [no ci]

This commit adds a semver to the ggml backend modules files.

The motivation for this is that the backends are currently loaded just a
file extension, for example .so on linux. With the introduction of
semantic versioning installing a new version should just work but since
these files don't have a version they would get overwritten. Adding the
semver to the library names allows multiple version to be supported and
the correct one will be loaded by the code.

I've only tested this on linux and need to test on mac and win.

* Revert "cmake : add semver to ggml backends [no ci]"

This reverts commit 53a6c58a07591951324c891b9986b2cffe5c7972.

* examples : update build-install.sh and set GGML_BACKEND_DIR

ggml/CMakeLists.txt

@@ -402,7 +402,7 @@ configure_package_config_file(
               GGML_BIN_INSTALL_DIR)
 
 write_basic_package_version_file(
-        ${CMAKE_CURRENT_BINARY_DIR}/ggml-version.cmake
+        ${CMAKE_CURRENT_BINARY_DIR}/ggml-config-version.cmake
     VERSION ${GGML_INSTALL_VERSION}
     COMPATIBILITY SameMajorVersion)
 
@@ -414,7 +414,7 @@ message(STATUS "ggml version: ${GGML_INSTALL_VERSION}")
 message(STATUS "ggml commit:  ${GGML_BUILD_COMMIT}")
 
 install(FILES ${CMAKE_CURRENT_BINARY_DIR}/ggml-config.cmake
-              ${CMAKE_CURRENT_BINARY_DIR}/ggml-version.cmake
+              ${CMAKE_CURRENT_BINARY_DIR}/ggml-config-version.cmake
         DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/ggml)
 
 if (MSVC)

ggml/cmake/ggml-config.cmake.in

@@ -113,6 +113,7 @@ set_and_check(GGML_LIB_DIR "@PACKAGE_GGML_LIB_INSTALL_DIR@")
 if(NOT TARGET ggml::ggml)
     find_package(Threads REQUIRED)
 
+    unset(GGML_LIBRARY CACHE)
     find_library(GGML_LIBRARY ggml
         REQUIRED
         HINTS ${GGML_LIB_DIR}
@@ -121,8 +122,10 @@ if(NOT TARGET ggml::ggml)
     add_library(ggml::ggml UNKNOWN IMPORTED)
     set_target_properties(ggml::ggml
         PROPERTIES
-            IMPORTED_LOCATION "${GGML_LIBRARY}")
+            IMPORTED_LOCATION "${GGML_LIBRARY}"
+            INTERFACE_INCLUDE_DIRECTORIES "${GGML_INCLUDE_DIR}")
 
+    unset(GGML_BASE_LIBRARY CACHE)
     find_library(GGML_BASE_LIBRARY ggml-base
         REQUIRED
         HINTS ${GGML_LIB_DIR}
@@ -132,6 +135,7 @@ if(NOT TARGET ggml::ggml)
     set_target_properties(ggml::ggml-base
         PROPERTIES
             IMPORTED_LOCATION "${GGML_BASE_LIBRARY}"
+            INTERFACE_INCLUDE_DIRECTORIES "${GGML_INCLUDE_DIR}"
             INTERFACE_LINK_LIBRARIES "${GGML_BASE_INTERFACE_LINK_LIBRARIES}")
 
     set(_ggml_all_targets "")
@@ -140,6 +144,7 @@ if(NOT TARGET ggml::ggml)
             string(REPLACE "-" "_" _ggml_backend_pfx "${_ggml_backend}")
             string(TOUPPER "${_ggml_backend_pfx}" _ggml_backend_pfx)
 
+            unset(${_ggml_backend_pfx}_LIBRARY CACHE)
             find_library(${_ggml_backend_pfx}_LIBRARY ${_ggml_backend}
                 REQUIRED
                 HINTS ${GGML_LIB_DIR}