Update illumos support to the modern era (#24)

* Update Solaris / Illumos support

Old versions of Solaris did not have vasprintf, so darkhttpd defined one
gated behind an ifdef. Oracle Solaris 10 has had vasprintf since 2011.
Oracle Solaris 11 has had it since release. illumos (which also reports
as `__sun`) also has it in all current incarnations. As a result, this
ifdef'd block creates compiler errors due to a second definition of the
function. This commit removes the block.

This commit also adds `-lsendfile` to the Makefile for systems that
report as `SunOS` in `uname` (Solaris and Illumos), which is necessary
to link successfully in current day.

* Comment on manually specifying CC in readme

Some systems, including versions of illumos I use, do not have a `cc`
alias to the system C compiler. Arguably this is a flaw in the
distribution, but as a user, it's perhaps helpful to be reminded that
this is an option.

Makefile

@@ -1,6 +1,6 @@
 CC?=cc
 CFLAGS?=-O
-LIBS=`[ \`uname\` = "SunOS" ] && echo -lsocket -lnsl`
+LIBS=`[ \`uname\` = "SunOS" ] && echo -lsocket -lnsl -lsendfile`
 
 all: darkhttpd
 

README.md

@@ -48,6 +48,12 @@ Simply run make:
 make
 ```
 
+If `cc` is not on your `PATH` as an alias to your C compiler, you may need to specify it. For example,
+
+```
+CC=gcc make
+```
+
 ## How to run darkhttpd
 
 Serve /var/www/htdocs on the default port (80 if running as root, else 8080):

darkhttpd.c

@@ -381,16 +381,6 @@ static char *xstrdup(const char *src) {
     return dest;
 }
 
-#ifdef __sun /* unimpressed by Solaris */
-static int vasprintf(char **strp, const char *fmt, va_list ap) {
-    char tmp;
-    int result = vsnprintf(&tmp, 1, fmt, ap);
-    *strp = xmalloc(result+1);
-    result = vsnprintf(*strp, result+1, fmt, ap);
-    return result;
-}
-#endif
-
 /* vasprintf() that dies if it fails. */
 static unsigned int xvasprintf(char **ret, const char *format, va_list ap)
     __printflike(2,0);