Math library: add numerous C99 functions.

* configure: Detect all the new functions, with separate
tests for the unary and binary ones.

* arith.c (cbrt_s, erf_s, erfc_s, exp10_s, exp2_s,
expm1_s, gamma_s, j0_s, j1_s, lgamma_s, log1p_s, logb_s,
nearbyint_s, rint_s, significand_s, tgamma_s, y0_s, y1_s,
copysign_s, drem_s, fdim_s, fmax_s, fmin_s, hypot_s,
jn_s, ldexp_s, nextafter_s, remainder_s, scalb_s, scalbln_s,
yn_s, r_copysign_s, r_drem_s, r_fdim_s, r_fmax_s, r_fmin_s,
hypot_s, r_jn_s, r_ldexp_s, r_nextafter_s, r_remainder_s,
r_scalb_s, scalbln_s, r_yn_s): New symbol variables.
(not_available): New static function.
(cbrt_wrap, erf_wrap, erfc_wrap, exp10_wrap, exp2_wrap,
expm1_wrap, gamma_wrap, j0_wrap, j1_wrap, lgamma_wrap,
log1p_wrap, logb_wrap, nearbyint_wrap, rint_wrap,
significand_wrap, tgamma_wrap, y0_wrap, y1_wrap,
copysign_wrap, drem_wrap, fdim_wrap, fmax_wrap,
fmin_wrap, hypot_wrap, jn_wrap, ldexp_wrap,
nextafter_wrap, remainder_wrap, scalb_wrap, scalbln_wrap,
yn_wrap): New static functions.
(arith_set_entries, arith_instantiate): New static functions.
(arith_init): Initialize symbols and instantiate functions
via autoload mechanism. In a program that doesn't use the
functions, we suffer only the overhead of interning the symbols.

* lib.h (UNUSED): New macro for GCC unused attribute.

* txr.1: Documented.

* stdlib/doc-syms.tl: Updated.

1 files changed, 44 insertions, 0 deletions

diff --git a/configure b/configure
index 02468f73..8c39cd4d 100755
--- a/configure
+++ b/configure
@@ -2918,6 +2918,50 @@ else
   printf "no\n"
 fi
 
+for fun in cbrt erf erfc exp10 exp2 expm1 \
+           gamma j0 j1 lgamma log1p logb \
+           nearbyint pow10 rint significand tgamma y0 y1
+do
+  printf "Checking for %s function ... " $fun
+  cat > conftest.c <<!
+#include <math.h>
+
+int main(void)
+{
+  double a = $fun(0.5);
+  return 0;
+}
+!
+  if conftest ; then
+    printf "yes\n"
+    printf "#define HAVE_%s 1\n" $(echo $fun | tr '[a-z]' '[A-Z]') >> config.h
+  else
+    printf "no\n"
+  fi
+done
+
+for fun in copysign drem fdim fmax fmin \
+           frexp hypot jn ldexp modf \
+           nextafter nexttoward remainder scalb scalbln yn
+do
+  printf "Checking for %s function ... " $fun
+  cat > conftest.c <<!
+#include <math.h>
+
+int main(void)
+{
+  double a = $fun(0.5, 0.5);
+  return 0;
+}
+!
+  if conftest ; then
+    printf "yes\n"
+    printf "#define HAVE_%s 1\n" $(echo $fun | tr '[a-z]' '[A-Z]') >> config.h
+  else
+    printf "no\n"
+  fi
+done
+
 printf "Checking for glob ... "
 
 cat > conftest.c <<!