[Buildroot] [git commit branch/2025.08.x] package/vulkan-headers: needs C++

[Thomas Perale]

commit: https://git.buildroot.net/buildroot/commit/?id=e8394621f7d5ffc5afcf7c9c3e00f31f051c898f
branch: https://git.buildroot.net/buildroot/commit/?id=refs/heads/2025.08.x

Since Buildroot commit [1] "package/vulkan-{headers,loader,tools}:
bump to 1.4.317 release", the vulkan-headers package is failing at
configuration time with toolchains without C++ support, with error:

    The C++ compiler
      "/bin/false"
    is not able to compile a simple test program.

This is due to upstream commit [2], which added CXX to the CMake
project file.

This commit fixes the issue by adding the C++ dependency.

Fixes:
https://autobuild.buildroot.org/results/10f63398940d52be9a8ee306daf4203ceca25eb8

[1] https://gitlab.com/buildroot.org/buildroot/-/commit/52664093dee0f280db191c391167848dc5b09745
[2] https://github.com/KhronosGroup/Vulkan-Headers/commit/85256c712ce9ee9755ae74faacc3e6a1d2c5eddf

Signed-off-by: Julien Olivain <ju.o at free.fr>
(cherry picked from commit 2f6a82b633643ce4d1e30579e345497aea3d2a1c)
Signed-off-by: Thomas Perale <thomas.perale at mind.be>
---
 package/vulkan-headers/Config.in | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/package/vulkan-headers/Config.in b/package/vulkan-headers/Config.in
index c0fc8f20b0..fdab31893f 100644
--- a/package/vulkan-headers/Config.in
+++ b/package/vulkan-headers/Config.in
@@ -1,7 +1,11 @@
 config BR2_PACKAGE_VULKAN_HEADERS
 	bool "vulkan-headers"
+	depends on BR2_INSTALL_LIBSTDCPP
 	help
 	  The Khronos official Vulkan header files and API
 	  registry.
 
 	  https://github.com/KhronosGroup/Vulkan-Headers
+
+comment "vulkan-headers needs a toolchain w/ C++"
+	depends on !BR2_INSTALL_LIBSTDCPP