Normalize the path to remove duplicate / separators rather than

possibly altering the path with realpath(3).  Leave sym links
as is in path components.  This is also cheaper than realpath(3),
and works on platforms that don't have realpath(3).

Note: if this is accepted, the check for realpath in configure.ac
can be removed, and some docs that mention realpath will be adjusted.

libpkgconf/path.c

@@ -231,12 +231,39 @@ pkgconf_path_free(pkgconf_list_t *dirlist)
 	}
 }
 
+static char *
+normpath(const char *path)
+{
+	if (!path)
+		return NULL;
+
+	char *copy = strdup(path);
+	if (NULL == copy)
+		return NULL;
+	char *ptr = copy;
+
+	for (int ii = 0; copy[ii]; ii++)
+	{
+		*ptr++ = path[ii];
+		if ('/' == path[ii])
+		{
+			ii++;
+			while ('/' == path[ii])
+				ii++;
+			ii--;
+		}
+	}
+	*ptr = '\0';
+
+	return copy;
+}
+
 /*
  * !doc
  *
  * .. c:function:: bool pkgconf_path_relocate(char *buf, size_t buflen)
  *
- *    Relocates a path, possibly calling realpath() or cygwin_conv_path() on it.
+ *    Relocates a path, possibly calling normpath() or cygwin_conv_path() on it.
  *
  *    :param char* buf: The path to relocate.
  *    :param size_t buflen: The buffer length the path is contained in.
@@ -267,10 +294,10 @@ pkgconf_path_relocate(char *buf, size_t buflen)
 		if (*ti == '\\')
 			*ti = '/';
 	}
-#elif defined(HAVE_REALPATH)
+#else
 	char *tmpbuf;
 
-	if ((tmpbuf = realpath(buf, NULL)) != NULL)
+	if ((tmpbuf = normpath(buf)) != NULL)
 	{
 		size_t tmpbuflen = strlen(tmpbuf);
 		if (tmpbuflen > buflen)
@@ -282,9 +309,6 @@ pkgconf_path_relocate(char *buf, size_t buflen)
 		pkgconf_strlcpy(buf, tmpbuf, buflen);
 		free(tmpbuf);
 	}
-#else
-	(void) buf;
-	(void) buflen;
 #endif
 
 	return true;