New Makefile structure; added compatibility with Windows + Visual C + nmake.

mk/SingleUnix.mk

@@ -0,0 +1,38 @@
+# Copyright (c) 2017 Thomas Pornin <pornin@bolet.org>
+#
+# Permission is hereby granted, free of charge, to any person obtaining 
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be 
+# included in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
+# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+# ======================================================================
+
+# This file sets variables for use with a SingleUnix-compatible 'make'
+# utility.
+
+# Load generic default.
+include mk/Defaults.mk
+
+# Path separator.
+P = /
+
+# Default configuration is 'Unix' (native build on a Unix-like system).
+CONF = Unix
+
+include conf/$(CONF).mk
+include mk/Rules.mk