Remove some potential double free

Signed-off-by: Bryce Harrington <b.harrington@samsung.com>
Reviewed-by: Uli Schlachter <psychon@znc.in>
Fix some memory leaks found by scan-build, the LLVM/Clang static analyzer

Signed-off-by: Bryce Harrington <b.harrington@samsung.com>
Reviewed-by: Uli Schlachter <psychon@znc.in>
glx: Use GLX_NONE in place of None

Use "GLX_NONE" in rgb and rgba attributes instead of
"None" in cairo-boilerplate-glx.c

Signed-off-by: Ravi Nanjundappa <nravi.n@samsung.com>
Reviewed-by: Bryce Harrington <b.harrington@samsung.com>