evas_gl : Fixed macro substitution bug in evas_gl

evas_gl : Fixed macro substitution bug in evas_gl

In evas_gl_api_ext_def.h there're calls such as:

    _EVASGL_EXT_DRVNAME(EGL_KHR_image_base)

    The macro is defined in evas_gl_api_ext.c as:

    (strstr(glexts, #name) != NULL || strstr(glueexts, #name) != NULL)

    if (_EVASGL_EXT_CHECK_SUPPORT(name)) *ext_support = 1;

    But EGL_KHR_image_base is itself a macro, which is defined
    in EGL/eglext.h like this:

    Thus, the _EVASGL_EXT_CHECK_SUPPORT macro will unwrap into:

    (strstr(glexts, "1") != NULL || strstr(glueexts, "1") != NULL)

    instead of intended:

    (strstr(glexts, "EGL_KHR_image_base") != NULL ||
     strstr(glueexts, "EGL_KHR_image_base") != NULL)

    This patch fixes this by applying stringification earlier in
    _EVASGL_EXT_DRVNAME

Bugfix reported by jinhyung.jo@samsung.com