Make --enable-dynamic a tristate option.

Some programs will by default be linked against static
liblzma and some against shared liblzma. --enable-dynamic
now allows overriding the default to both directions
(all dynamic or all static) even when building both
shared and static liblzma.

This is quite messy compared to how simple thing it is supposed
to be. The complexity is mostly due to Windows support.

configure.ac

@@ -375,37 +375,35 @@ AC_MSG_RESULT([$enable_threads])
 # xz/xzdec/lzmadec linkage against liblzma #
 ############################################
 
-# Link the command line tool statically against liblzma unless using
-# --enable-dynamic. Using static liblzma gives a little bit faster executable
-# on x86, because no register is wasted for PIC. We also have one dependency
-# less, which allows users to more freely copy the xz binary to other boxes.
-# However, I wouldn't be surprised if distro maintainers still prefer dynamic
-# linking, so let's make it easy for them.
+# Link the xz, xzdec, and lzmadec command line tools against static liblzma
+# unless using --enable-dynamic. Using static liblzma gives a little bit
+# faster executable on x86, because no register is wasted for PIC. We also
+# have one dependency less, which allows users to more freely copy the xz
+# binary to other boxes. However, I wouldn't be surprised if distro
+# maintainers still prefer dynamic linking, so let's make it easy for them.
 
-AC_MSG_CHECKING([how command line tools should be linked against liblzma])
-AC_ARG_ENABLE([dynamic], [AC_HELP_STRING([--enable-dynamic],
-			[Link command line tools dynamically against liblzma.
-			The default is to use static liblzma if it was
-			built.])],
-		[], [enable_dynamic=no])
+AC_MSG_CHECKING([how programs should be linked against liblzma])
+AC_ARG_ENABLE([dynamic], [AC_HELP_STRING([--enable-dynamic=TYPE],
+			[Set how command line tools are linked against liblzma.
+			TYPE can be mixed, yes, or no. The default is mixed.])],
+		[], [enable_dynamic=mixed])
 case $enable_dynamic in
+	mixed)
+		AC_MSG_RESULT([mixed (some dynamically, some statically)])
+		;;
 	yes)
-		STATIC_CPPFLAGS=
-		STATIC_LDFLAGS=
 		AC_MSG_RESULT([dynamically])
 		;;
 	no)
-		STATIC_CPPFLAGS="-DLZMA_API_STATIC"
-		STATIC_LDFLAGS="-static"
 		AC_MSG_RESULT([statically])
 		;;
 	*)
 		AC_MSG_RESULT([])
-		AC_MSG_ERROR([--enable-dynamic accepts only \`yes' or \`no'])
+		AC_MSG_ERROR([--enable-dynamic accepts only \`mixed', \`yes', or \`no'])
 		;;
 esac
-AC_SUBST([STATIC_CPPFLAGS])
-AC_SUBST([STATIC_LDFLAGS])
+# We use the actual results later, because we don't know yet
+# if --disable-shared or --disable-static was used.
 
 
 ###############################################################################
@@ -648,6 +646,45 @@ AM_CONDITIONAL([COND_GNULIB], test -n "$LIBOBJS")
 # Add default AM_CFLAGS.
 AC_SUBST([AM_CFLAGS])
 
+# Set additional flags for static/dynamic linking. The idea is that every
+# program (not library) being built will use either STATIC_{CPPFLAGS,LDFLAGS}
+# or DYNAMIC_{CPPFLAGS,LDFLAGS} depending on which type of linkage is
+# preferred. These preferences get overriden by use of --disable-static,
+# --disable-shared, or --enable-dynamic.
+#
+# This is quite messy, because we want to use LZMA_API_STATIC when linking
+# against static liblzma. It's needed on Windows.
+if test "x$enable_static" = xno; then
+	enable_dynamic=yes
+fi
+if test "x$enable_shared" = xno; then
+	enable_dynamic=no
+fi
+case $enable_dynamic in
+	yes)
+		STATIC_CPPFLAGS=
+		STATIC_LDFLAGS=
+		DYNAMIC_CPPFLAGS=
+		DYNAMIC_LDFLAGS=
+		;;
+	mixed)
+		STATIC_CPPFLAGS="-DLZMA_API_STATIC"
+		STATIC_LDFLAGS="-static"
+		DYNAMIC_CPPFLAGS=
+		DYNAMIC_LDFLAGS=
+		;;
+	no)
+		STATIC_CPPFLAGS="-DLZMA_API_STATIC"
+		STATIC_LDFLAGS="-static"
+		DYNAMIC_CPPFLAGS="-DLZMA_API_STATIC"
+		DYNAMIC_LDFLAGS="-static"
+		;;
+esac
+AC_SUBST([STATIC_CPPFLAGS])
+AC_SUBST([STATIC_LDFLAGS])
+AC_SUBST([DYNAMIC_CPPFLAGS])
+AC_SUBST([DYNAMIC_LDFLAGS])
+
 # This is needed for src/scripts.
 xz=`echo xz | sed "$program_transform_name"`
 AC_SUBST([xz])