checkasm: lls: Use relative tolerances rather than absolute ones

Depending on the magnitude of the output values, the potential
errors can be larger.

This fixes errors in the lls tests on x86_32 for some seeds,
observed with GCC 11 (on Ubuntu 22.04, with the distro compiler,
with -m32).

Signed-off-by: Martin Storsjö <martin@martin.st>
(cherry picked from commit 6668268e16)

tests/checkasm/lls.c

@@ -46,28 +46,32 @@ static void test_update(LLSModel *lls, const double *var)
     call_new(lls, var);
 
     for (size_t i = 0; i < lls->indep_count; i++)
-        for (size_t j = i; j < lls->indep_count; j++)
+        for (size_t j = i; j < lls->indep_count; j++) {
+            double eps = FFMAX(2 * DBL_EPSILON * fabs(refcovar[i][j]),
+                               8 * DBL_EPSILON);
             if (!double_near_abs_eps(refcovar[i][j], lls->covariance[i][j],
-                                     8 * DBL_EPSILON)) {
+                                     eps)) {
                 fprintf(stderr, "%zu, %zu: %- .12f - %- .12f = % .12g\n", i, j,
                         refcovar[i][j], lls->covariance[i][j],
                         refcovar[i][j] - lls->covariance[i][j]);
                 fail();
             }
+        }
 
     bench_new(lls, var);
 }
 
-#define EPS 0.2
 static void test_evaluate(LLSModel *lls, const double *param, int order)
 {
-    double refprod, newprod;
+    double refprod, newprod, eps;
     declare_func_float(double, LLSModel *, const double *, int);
 
     refprod = call_ref(lls, param, order);
     newprod = call_new(lls, param, order);
 
-    if (!double_near_abs_eps(refprod, newprod, EPS)) {
+    eps = FFMAX(2 * DBL_EPSILON * fabs(refprod), 0.2);
+
+    if (!double_near_abs_eps(refprod, newprod, eps)) {
         fprintf(stderr, "%- .12f - %- .12f = % .12g\n",
                 refprod, newprod, refprod - newprod);
         fail();