Build: add compatibility between precompiled libraries and new glibc

On Linux, precompiled libraries may be made with a glibc version that is
incompatible with the system libraries that Blender is built on. To solve
this we add a few -ffast-math symbols that can be missing.

Differential Revision: https://developer.blender.org/D6930

intern/libc_compat/libc_compat.c

@@ -0,0 +1,109 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * The Original Code is Copyright (C) 2020 Blender Foundation.
+ * All rights reserved.
+ */
+
+/* On Linux, precompiled libraries may be made with an glibc version that is
+ * incompatible with the system libraries that Blender is built on. To solve
+ * this we add a few -ffast-math symbols that can be missing. */
+
+#include <math.h>
+
+double __exp_finite(double x);
+double __acos_finite(double x);
+double __asin_finite(double x);
+double __log2_finite(double x);
+double __log10_finite(double x);
+double __log_finite(double x);
+double __pow_finite(double x, double y);
+float __expf_finite(float x);
+float __acosf_finite(float x);
+float __asinf_finite(float x);
+float __log2f_finite(float x);
+float __log10f_finite(float x);
+float __logf_finite(float x);
+float __powf_finite(float x, float y);
+
+double __exp_finite(double x)
+{
+  return exp(x);
+}
+
+double __acos_finite(double x)
+{
+  return acos(x);
+}
+
+double __asin_finite(double x)
+{
+  return asin(x);
+}
+
+double __log2_finite(double x)
+{
+  return log2(x);
+}
+
+double __log10_finite(double x)
+{
+  return log10(x);
+}
+
+double __log_finite(double x)
+{
+  return log(x);
+}
+
+double __pow_finite(double x, double y)
+{
+  return pow(x, y);
+}
+
+float __expf_finite(float x)
+{
+  return expf(x);
+}
+
+float __acosf_finite(float x)
+{
+  return acosf(x);
+}
+
+float __asinf_finite(float x)
+{
+  return asinf(x);
+}
+
+float __log2f_finite(float x)
+{
+  return log2f(x);
+}
+
+float __log10f_finite(float x)
+{
+  return log10f(x);
+}
+
+float __logf_finite(float x)
+{
+  return logf(x);
+}
+
+float __powf_finite(float x, float y)
+{
+  return powf(x, y);
+}