Update header location from gcc to clang

[nsrahmad]

Also generated spec files from llvm-8 version of c2ffi Fixes #122

[VictorAlbertsson]

Issue:

;     (FORMAT STREAM
;             "name ~S flags ~A num-texture-formats ~A texture-formats TBD max-texture-width ~
;   ~A max-texture-height ~A"
;             (SDL2::RINFO :NAME) (SDL2::RINFO :FLAGS)
;             (SDL2::RINFO :NUM-TEXTURE-FORMATS) (SDL2::RINFO :MAX-TEXTURE-WIDTH)
;             (SDL2::RINFO :MAX-TEXTURE-HEIGHT))
;
; caught ERROR:
;   during macroexpansion of
;   (FORMATTER
;    "name ~S flags ~A num-texture-formats ~A texture-formats TBD max-texture-width ~
;   ~A max-texture-height ~A").
;   Use *BREAK-ON-SIGNALS* to intercept.
;
;    error in FORMAT: Unknown directive (character: Return)
;     name ~S flags ~A num-texture-formats ~A texture-formats TBD max-texture-width ~
;   ~A max-texture-height ~A
;

Solution: At the end of line 12, remove the ~ and the line break. https://github.com/lispgames/cl-sdl2/blob/2eaf15951cf98d3c4709350c68db1341dade55e6/src/render.lisp#L9-L19

[mfiano]

This is only an issue on the very old SBCL version specified in the original issue of #122. Updating SBCL will fix it. tilde return is used here how it's meant to be used for conforming Common Lisp.

[theneosloth]

Still encountering this issue after updating to SBCL 1.5.9 on Windows 10 64 bit