[PATCH v2 modular 3/3] build.sh: comment the supported systems and how they are detected

[Gaetan Nadon]

For many, build.sh is the first encounter to X.Org or even UNIX code.
This comment should help them understand why certain packages cannot be
built on thier system.

Signed-off-by: Gaetan Nadon <memsize at videotron.ca>
---
 build.sh |   28 ++++++++++++++++++++++++++--
 1 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/build.sh b/build.sh
index f996a0f..3f66d44 100755
--- a/build.sh
+++ b/build.sh
@@ -1,10 +1,34 @@
 #!/bin/sh
-#
-# Note on portability:
+
+# Script Portability
 # This script is intended to run on any platform supported by X.Org.
 # The Autoconf generated configure script is a good reference as to what is permitted.
 # Basically, it should be able to run in a Bourne shell.
 
+# Build Exceptions
+# Not all packages can be built on all systems.
+# uname -s   Description
+# --------   --------------------------------------------------------------------------
+# CYGWIN*    a Unix-like environment and command-line interface for Microsoft Windows
+# Darwin     a layer of Mac OS X comprising the kernel, drivers and BSD technologies
+# Dragonfly  a Unix-like operating system created as a fork of FreeBSD 4.8
+# FreeBSD    a free Unix-like operating system descended from AT&T UNIX via BSD UNIX
+# Linux      a Unix-like operating systems with GNU software and Linux kernel
+# GNU        a Unix-like operating system developed by the GNU project - Hurd microkernel
+# GNU/*      a Unix-like operating system with GNU software but a non Linux kernel
+# NetBSD     an open source version of the Unix-derivative Berkeley Software Distribution
+# OpenBSD    a Unix-like operating system descended from Berkeley Software Distribution
+# SunOS      a Unix system developed by Sun Microsystems under the Solaris brand
+#
+# Not all packages can be built on all cpus.
+# uname -m   Description
+# --------   --------------------------------------------------------------------------
+# i*86       CPUs supporting the Intel 8086 instruction set architecture (ISA)
+# x86_64     CPUs supporting x86 ISA with 64 bit extensions
+# amd64      CPUs supporting x86 ISA with 64 bit extensions
+# sparc      a RISC instruction set architecture (ISA) developed by Sun Microsystems
+# sparc64    a RISC instruction set architecture (ISA) developed by Sun Microsystems
+
 envoptions() {
 cat << EOF
 Environment variables specific to build.sh:
-- 
1.6.0.4