This separates the 32-bit sysv/linux/bsd code from the 64-bit linux

code, and makes it possible to link code compiled with different
options to those used to compile libffi.  For example, a
-mlong-double-128 libffi can be used with -mlong-double-64 code.

Using the return value area as a place to pass parameters wasn't such
a good idea, causing a failure of cls_ulonglong.c.  I didn't see this
when running the mainline gcc libffi testsuite because that version of
the test is inferior to the upstreamm libffi test.

Using NUM_FPR_ARG_REGISTERS rather than NUM_FPR_ARG_REGISTERS64 meant
that a parameter save area could be allocated before it was strictly
necessary.  Wrong but harmless.  Found when splitting apart ffi.c
into 32-bit and 64-bit support.

configure.ac

@@ -66,6 +66,7 @@ dnl The -no-testsuite modules omit the test subdir.
 AM_CONDITIONAL(TESTSUBDIR, test -d $srcdir/testsuite)
 
 TARGETDIR="unknown"
+HAVE_LONG_DOUBLE_VARIANT=0
 case "$host" in
   aarch64*-*-*)
 	TARGET=AARCH64; TARGETDIR=aarch64
@@ -226,6 +227,7 @@ case "$host" in
 
   powerpc*-*-linux* | powerpc-*-sysv*)
 	TARGET=POWERPC; TARGETDIR=powerpc
+	HAVE_LONG_DOUBLE_VARIANT=1
 	;;
   powerpc-*-amigaos*)
 	TARGET=POWERPC; TARGETDIR=powerpc
@@ -241,6 +243,7 @@ case "$host" in
 	;;
   powerpc-*-freebsd* | powerpc-*-openbsd*)
 	TARGET=POWERPC_FREEBSD; TARGETDIR=powerpc
+	HAVE_LONG_DOUBLE_VARIANT=1
 	;;
   powerpc64-*-freebsd*)
 	TARGET=POWERPC; TARGETDIR=powerpc
@@ -333,14 +336,20 @@ AC_CHECK_SIZEOF(long double)
 # Also AC_SUBST this variable for ffi.h.
 if test -z "$HAVE_LONG_DOUBLE"; then
   HAVE_LONG_DOUBLE=0
-  if test $ac_cv_sizeof_double != $ac_cv_sizeof_long_double; then
-    if test $ac_cv_sizeof_long_double != 0; then
+  if test $ac_cv_sizeof_long_double != 0; then
+    if test $HAVE_LONG_DOUBLE_VARIANT != 0; then
+      AC_DEFINE(HAVE_LONG_DOUBLE_VARIANT, 1, [Define if you support more than one size of the long double type])
       HAVE_LONG_DOUBLE=1
-      AC_DEFINE(HAVE_LONG_DOUBLE, 1, [Define if you have the long double type and it is bigger than a double])
+    else
+      if test $ac_cv_sizeof_double != $ac_cv_sizeof_long_double; then
+        HAVE_LONG_DOUBLE=1
+        AC_DEFINE(HAVE_LONG_DOUBLE, 1, [Define if you have the long double type and it is bigger than a double])
+      fi
     fi
   fi
 fi
 AC_SUBST(HAVE_LONG_DOUBLE)
+AC_SUBST(HAVE_LONG_DOUBLE_VARIANT)
 
 AC_C_BIGENDIAN