modf-ieee: Work around test failures on *BSD, IRIX, OSF/1, Cygwin. * m4/modf-ieee.m4: New file. * m4/modf.m4 (gl_FUNC_MODF): If gl_FUNC_MODF_IEEE is present, test whether modf works with NaN and Inf. Replace it if not. * lib/math.in.h (modf): New declaration. * lib/modf.c: New file. * m4/math_h.m4 (gl_MATH_H): Test whether modf is declared. (gl_MATH_H_DEFAULTS): Initialize GNULIB_MODF, REPLACE_MODF. * modules/math (Makefile.am): Substitute GNULIB_MODF, REPLACE_MODF. * modules/modf (Files): Add lib/modf.c. (Depends-on): Add math, isfinite, trunc, isinf. (configure.ac): Addrange to compile lib/modf.c if needed. * modules/modf-ieee (Files): Add m4/modf-ieee.m4, m4/minus-zero.m4, m4/signbit.m4. (configure.ac): Invoke gl_FUNC_MODF_IEEE. * tests/test-math-c++.cc: Check the declaration of modf. * doc/posix-functions/modf.texi: Mention the modf-ieee module.

--- a/modules/math
+++ b/modules/math
@@ -72,6 +72,7 @@
 	      -e 's/@''GNULIB_LOGL''@/$(GNULIB_LOGL)/g' \
 	      -e 's/@''GNULIB_LOG10F''@/$(GNULIB_LOG10F)/g' \
 	      -e 's/@''GNULIB_LOG10L''@/$(GNULIB_LOG10L)/g' \
+	      -e 's/@''GNULIB_MODF''@/$(GNULIB_MODF)/g' \
 	      -e 's/@''GNULIB_MODFF''@/$(GNULIB_MODFF)/g' \
 	      -e 's/@''GNULIB_MODFL''@/$(GNULIB_MODFL)/g' \
 	      -e 's/@''GNULIB_POWF''@/$(GNULIB_POWF)/g' \
@@ -190,6 +191,7 @@
 	      -e 's|@''REPLACE_ISNAN''@|$(REPLACE_ISNAN)|g' \
 	      -e 's|@''REPLACE_ITOLD''@|$(REPLACE_ITOLD)|g' \
 	      -e 's|@''REPLACE_LDEXPL''@|$(REPLACE_LDEXPL)|g' \
+	      -e 's|@''REPLACE_MODF''@|$(REPLACE_MODF)|g' \
 	      -e 's|@''REPLACE_NAN''@|$(REPLACE_NAN)|g' \
 	      -e 's|@''REPLACE_ROUND''@|$(REPLACE_ROUND)|g' \
 	      -e 's|@''REPLACE_ROUNDF''@|$(REPLACE_ROUNDF)|g' \