Expugne executable stack pattern

[fsaad]

librvg dynamically creates functions on the stack, which is a GNU extension and requires compiling with -z,execstack. This pattern should be avoided to improve portability.

librvg/generate.h

Lines 96 to 126 in eb31050

	/* Make a dual distribution function. */
	#define MAKE_DDF(ddf, cdf, sf) \
	const double ddf##__cutoff = quantile(cdf, nextafterf(.5, 1)); \
	const bool ddf##__sign = signbit(ddf##__cutoff); \
	bool ddf##__abort = false; \
	if(0.5 < cdf(nextafter(ddf##__cutoff, -INFINITY))) { \
	fprintf(stderr, "Invalid CDF detected.\n"); \
	ddf##__abort = true; \
	} \
	if(0.5 <= sf(ddf##__cutoff)) { \
	fprintf(stderr, "Invalid SF detected.\n"); \
	ddf##__abort = true; \
	} \
	if (ddf##__abort) { \
	exit(1); \
	} \
	void ddf(double x, bool * d, float * q) { \
	if ((x < ddf##__cutoff) \
	|| ((x == ddf##__cutoff) \
	&& signbit(x) \
	&& !(ddf##__sign))) { \
	*d = 0; \
	*q = cdf(x); \
	} else { \
	*d = 1; \
	*q = sf(x); \
	} \
	assert(check_ddf_val(*d, *q)); \
	}
	#endif