Test availability of MESA_query_driver with different platforms

gbm_test.cpp

// Compile with g++ -o gbm_test.bin gbm_test.cpp -lgbm -lGL -lEGL -I/usr/include/libdrm -I/usr/include/EGL -ldrm
#include <iostream>
#include <xf86drm.h>
#include <fcntl.h>
#include <gbm.h>
#include <EGL/egl.h>
#include <EGL/eglext.h>
#include <drm.h>
#include <string> 

typedef const char *eglGetDisplayDriverName_t(EGLDisplay disp);
typedef const char *eglGetDisplayDriverconfig_t(EGLDisplay disp);

int main() {
    EGLint major = 0, minor = 0;

    EGLBoolean binded = eglBindAPI(EGL_OPENGL_API);
    if (!binded) {
        std::cout << "Failed to bind EGL API" << std::endl;
        return 0;
    }

    auto driverName = (eglGetDisplayDriverName_t *) eglGetProcAddress("eglGetDisplayDriverName");
    auto driverConfig = (eglGetDisplayDriverconfig_t *) eglGetProcAddress("eglGetDisplayDriverConfig");
    
    
    EGLDisplay eglDpy = eglGetDisplay(EGL_DEFAULT_DISPLAY);
        
    if (eglDpy == EGL_NO_DISPLAY) {
        std::cout << "Failed to get display" << std::endl;
        return 1;
    }

    EGLBoolean initialized = eglInitialize(eglDpy, &major, &minor);
    if (initialized == EGL_FALSE) {
        std::cout << "Failed to initialize EGL" << std::endl;
        return 1;
    }
    
    const char *extensions = eglQueryString(eglDpy, EGL_EXTENSIONS);
    std::string extStr(extensions);
    std::size_t found = extStr.find("EGL_MESA_query_driver");
    if (found == std::string::npos) {
        std::cout << "Extension EGL_MESA_query_driver missing!" << std::endl;
        std::cout << "Available extensions: " << extensions << std::endl;
        return 1;
    }
    
    std::cout << "Extension EGL_MESA_query_driver found!" << std::endl;
    std::cout << "Querying driver name..." << std::endl;
    
    const char *name = (* driverName) (eglDpy);
    if (name != nullptr) {
        std::cout << "Driver is named " << name << std::endl;
    }

    std::cout << "Querying driver config..." << std::endl;
    const char *configsFound = (* driverConfig) (eglDpy);
    if (configsFound != nullptr) {
        std::cout << "Driver has the configs: ";
        std::cout << configsFound << std::endl;
    }

    eglTerminate(eglDpy);
    

    return 0;
}

Executing with EGL_PLATFORM=x11 ./gbm_test.bin works as expected and the extension EGL_MESA_query_driver is available.
Executing with EGL_PLATFORM=gbm ./gbm_test.bin fails, saying that the extension is not available.