More NetBSD fixes (w/ patch)

Cast input to tolower() to unsigned char to work around how tolower() is
implemented on NetBSD.

Also, use CPPFLAGS (rather than overriding CFLAGS) for the
NetBSD/DragonFly build example.

Corresponding to flashrom svn r905.

Signed-off-by: Jonathan A. Kollasch <jakllsch@kollasch.net>
Acked-by: Michael Karcher <flashrom@mkarcher.dialup.fu-berlin.de>
diff --git a/README b/README
index 3082f71..0150e90 100644
--- a/README
+++ b/README
@@ -68,7 +68,7 @@
 To compile on NetBSD or DragonFly BSD, use:
 
  ln -s /usr/pkg/include/pciutils pci
- gmake CFLAGS=-I. LDFLAGS="-L/usr/pkg/lib -Wl,-rpath-link,/usr/pkg/lib"
+ gmake CPPFLAGS=-I. LDFLAGS="-L/usr/pkg/lib -Wl,-rpath-link,/usr/pkg/lib"
 
 To compile and run on Darwin/Mac OS X: