Add compat/unsetenv.c .

Implement a (slow) unsetenv() for older systems.
Signed-off-by: NJason Riedy <ejr@cs.berkeley.edu>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Makefile

@@ -232,6 +232,7 @@ ifeq ($(uname_S),SunOS)
 	SHELL_PATH = /bin/bash
 	NO_STRCASESTR = YesPlease
 	ifeq ($(uname_R),5.8)
+		NO_UNSETENV = YesPlease
 		NO_SETENV = YesPlease
 	endif
 	INSTALL = ginstall
@@ -355,6 +356,10 @@ ifdef NO_SETENV
 	COMPAT_CFLAGS += -DNO_SETENV
 	COMPAT_OBJS += compat/setenv.o
 endif
+ifdef NO_SETENV
+	COMPAT_CFLAGS += -DNO_UNSETENV
+	COMPAT_OBJS += compat/unsetenv.o
+endif
 ifdef NO_MMAP
 	COMPAT_CFLAGS += -DNO_MMAP
 	COMPAT_OBJS += compat/mmap.o

compat/unsetenv.c

+#include <stdlib.h>
+#include <string.h>
+
+void gitunsetenv (const char *name)
+{
+     extern char **environ;
+     int src, dst;
+     size_t nmln;
+
+     nmln = strlen(name);
+
+     for (src = dst = 0; environ[src]; ++src) {
+	  size_t enln;
+	  enln = strlen(environ[src]);
+	  if (enln > nmln) {
+               /* might match, and can test for '=' safely */
+	       if (0 == strncmp (environ[src], name, nmln)
+		   && '=' == environ[src][nmln])
+		    /* matches, so skip */
+		    continue;
+	  }
+	  environ[dst] = environ[src];
+	  ++dst;
+     }
+     environ[dst] = NULL;
+}

connect.c

+#include "git-compat-util.h"
 #include "cache.h"
 #include "pkt-line.h"
 #include "quote.h"

git-compat-util.h

@@ -63,6 +63,11 @@ extern int gitfakemunmap(void *start, size_t length);
 extern int gitsetenv(const char *, const char *, int);
 #endif
 
+#ifdef NO_UNSETENV
+#define unsetenv gitunsetenv
+extern void gitunsetenv(const char *);
+#endif
+
 #ifdef NO_STRCASESTR
 #define strcasestr gitstrcasestr
 extern char *gitstrcasestr(const char *haystack, const char *needle);