package/libssh: fix build failure

When compiling libssh without a C++ cross-compiler the build will fail.

This patch remove the CMake C++ dependency to build libssh. That dependency
is only used for the code coverage tool and is not required to build the
library.

Fixes:
  - http://autobuild.buildroot.org/results/927/92794da6346b856ad74f14f87cc51415871cb5d2/
  - http://autobuild.buildroot.org/results/89d/89dcd4982e4061732de635f9e7669db1f257330c/
  - http://autobuild.buildroot.org/results/b3f/b3feff5c21defb53c65a3d5d06b13230cfed3317/
  - http://autobuild.buildroot.org/results/bc8/bc8338d2c61eaa7c98c99140de5c491b7528c4f3/
  - ...

Signed-off-by: Thomas Perale <thomas.perale@mind.be>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

package/libssh/0001-cmake-Only-enable-CXX-when-running-the-coverage.patch

@@ -0,0 +1,57 @@
+From 328ae3d2306c9f65b5e85a2be98a368c07287a05 Mon Sep 17 00:00:00 2001
+From: Thomas Perale <thomas.perale@mind.be>
+Date: Sat, 14 Sep 2024 21:07:30 +0200
+Subject: [PATCH] cmake: Only enable CXX when running the coverage
+
+Commit 25a678190c42b24076fdd805a8d7a722a8a9c798 introduced code coverage
+collection. That also introduced a dependency to CXX language.
+
+When cross-compiling libssh in an environment that doesn't have a C++ compiler
+the following error is raised: "No CMAKE_CXX_COMPILER could be found.".
+
+Since the C++ part is only needed for the coverage part, this commit only enable
+that language dependency when actually needing it.
+
+Signed-off-by: Thomas Perale <thomas.perale@mind.be>
+Upstream: https://gitlab.com/libssh/libssh-mirror/-/merge_requests/537
+---
+ CMakeLists.txt                    | 3 ++-
+ cmake/Modules/AddCMockaTest.cmake | 1 +
+ 2 files changed, 3 insertions(+), 1 deletion(-)
+
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index 13330ea3..5595a47a 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -9,7 +9,7 @@ list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_SOURCE_DIR}/cmake/Modules")
+ include(DefineCMakeDefaults)
+ include(DefineCompilerFlags)
+ 
+-project(libssh VERSION 0.11.1 LANGUAGES C CXX)
++project(libssh VERSION 0.11.1 LANGUAGES C)
+ 
+ # global needed variable
+ set(APPLICATION_NAME ${PROJECT_NAME})
+@@ -190,6 +190,7 @@ endif (WITH_SYMBOL_VERSIONING AND ABIMAP_FOUND)
+ 
+ # Coverage
+ if (WITH_COVERAGE)
++    ENABLE_LANGUAGE(CXX)
+     include(CodeCoverage)
+     setup_target_for_coverage_lcov(
+         NAME "coverage"
+diff --git a/cmake/Modules/AddCMockaTest.cmake b/cmake/Modules/AddCMockaTest.cmake
+index 79178183..f49961ba 100644
+--- a/cmake/Modules/AddCMockaTest.cmake
++++ b/cmake/Modules/AddCMockaTest.cmake
+@@ -117,6 +117,7 @@ function(ADD_CMOCKA_TEST _TARGET_NAME)
+         ${TARGET_SYSTEM_EMULATOR} ${_TARGET_NAME}
+     )
+     if (WITH_COVERAGE)
++        ENABLE_LANGUAGE(CXX)
+         include(CodeCoverage)
+         append_coverage_compiler_flags_to_target(${_TARGET_NAME})
+     endif (WITH_COVERAGE)
+-- 
+2.46.0
+