cmake: work around recent vcpkg update

In f1f5dff (cmake: installation support for git, 2020-06-26), we
added support for the CMake equivalent of `make install` that makes
use of multiple targets within one invocation of `install(TARGETS ...).
This is totally fine according to CMake's documentation at
https://cmake.org/cmake/help/latest/command/install.html#command:install).

And this was still fine even after ecf7ee3 (cmake(install):
include vcpkg dlls, 2021-01-08) where we started to use `vcpkg`'s CMake
scripts to ensure that the `.dll` files of Git's dependencies are also
installed.

However, with a recent update of `vcpkg`, the handling of local
dependencies was changed in a way that is incompatible with our CMake
definition. The symptom looks like this:

CMake Error at <worktree>/compat/vcbuild/vcpkg/scripts/buildsystems/vcpkg.cmake:734 (get_target_property):
  get_target_property() called with non-existent target "git;git-shell".
Call Stack (most recent call first):
  <worktree>/compat/vcbuild/vcpkg/scripts/buildsystems/vcpkg.cmake:784 (x_vcpkg_install_local_dependencies)
  CMakeLists.txt:821 (install)

The apparent reason for this breakage is that the `vcpkg` changes in
microsoft/vcpkg@1bb5ea10a3 no longer allows an
arbitrary number of targets to be specified in `install(TARGETS ...)`.

Let's work around this by feeding the target individually to the
`install(TARGETS ...)` function.

Signed-off-by: Johannes Schindelin <[email protected]>

Author: dscho

contrib/buildsystems/CMakeLists.txt

@@ -811,15 +811,19 @@ list(TRANSFORM git_shell_scripts PREPEND "${CMAKE_BINARY_DIR}/")
 list(TRANSFORM git_perl_scripts PREPEND "${CMAKE_BINARY_DIR}/")
 
 #install
-install(TARGETS git git-shell
+foreach(program ${PROGRAMS_BUILT})
+if(program STREQUAL "git" OR program STREQUAL "git-shell")
+install(TARGETS ${program}
 	RUNTIME DESTINATION bin)
+else()
+install(TARGETS ${program}
+	RUNTIME DESTINATION libexec/git-core)
+endif()
+endforeach()
+
 install(PROGRAMS ${CMAKE_BINARY_DIR}/git-cvsserver
 	DESTINATION bin)
 
-list(REMOVE_ITEM PROGRAMS_BUILT git git-shell)
-install(TARGETS ${PROGRAMS_BUILT}
-	RUNTIME DESTINATION libexec/git-core)
-
 set(bin_links
 	git-receive-pack git-upload-archive git-upload-pack)