Add configure-time checks for gamma and error functions.
diff --git a/configure.in b/configure.in
index 1f901fc..7b82312 100644
--- a/configure.in
+++ b/configure.in
@@ -3263,7 +3263,8 @@
[Define if tanh(-0.) is -0., or if platform doesn't have signed zeros])
fi
-AC_CHECK_FUNCS([acosh asinh atanh copysign expm1 finite hypot log1p round])
+AC_CHECK_FUNCS([acosh asinh atanh copysign erf erfc expm1 finite gamma])
+AC_CHECK_FUNCS([hypot lgamma log1p round tgamma])
AC_CHECK_DECLS([isinf, isnan, isfinite], [], [], [[#include <math.h>]])
LIBS=$LIBS_SAVE