fix the provided unsetenv for solaris to return an int like it's supposed to

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@16007 65c4cc65-6c06-0410-ace0-fbb531ad65f3

include/solaris-compat/compat.h

@@ -42,5 +42,5 @@ typedef unsigned int	u_int32_t;
 
 char* strsep(char** str, const char* delims);
 int setenv(const char *name, const char *value, int overwrite);
-void unsetenv(const char *name);
+int unsetenv(const char *name);
 #endif

strcompat.c

@@ -47,8 +47,8 @@ int setenv(const char *name, const char *value, int overwrite)
 	return putenv(buf);
 }
 
-void unsetenv(const char *name)
+int unsetenv(const char *name)
 {
-	setenv(name, "", 0);
+	return setenv(name, "", 0);
 }