Configure: using comma instead of space for passing -rpath value.

This variant will be more interoperable across various systems
and it's already used in Ruby module.

Otherwise, configure tests fail on NetBSD with:

  gcc: Missing argument for -Wl,-rpath

auto/modules/java

@@ -178,7 +178,7 @@ fi
 
 NXT_JAVA_LIB_SERVER_PATH="${NXT_JAVA_LIB_PATH}/server"
 
-NXT_JAVA_LDFLAGS="-L${NXT_JAVA_LIB_SERVER_PATH} -Wl,-rpath ${NXT_JAVA_LIB_SERVER_PATH} -ljvm"
+NXT_JAVA_LDFLAGS="-L${NXT_JAVA_LIB_SERVER_PATH} -Wl,-rpath,${NXT_JAVA_LIB_SERVER_PATH} -ljvm"
 
 
 nxt_found=no

auto/modules/php

@@ -111,8 +111,7 @@ if /bin/sh -c "${NXT_PHP_CONFIG} --version" >> $NXT_AUTOCONF_ERR 2>&1; then
         if [ "$NXT_PHP_LIB_PATH" != "" ]; then
             # "php-config --ldflags" does not contain path to libphp, but
             # contains usually path to libraries required by extensions.
-            NXT_PHP_LDFLAGS="-L${NXT_PHP_LIB_PATH} \
-                             -Wl,-rpath ${NXT_PHP_LIB_PATH}"
+            NXT_PHP_LDFLAGS="-L${NXT_PHP_LIB_PATH} -Wl,-rpath,${NXT_PHP_LIB_PATH}"
         fi
     fi
 

auto/modules/python

@@ -73,7 +73,7 @@ if /bin/sh -c "$NXT_PYTHON_CONFIG --prefix" >> $NXT_AUTOCONF_ERR 2>&1; then
 
     if [ "$NXT_PYTHON_LIB_PATH" != "" ]; then
         # "python-config --ldflags" may not contain path to libpython.
-        NXT_PYTHON_LDFLAGS="-L$NXT_PYTHON_LIB_PATH -Wl,-rpath $NXT_PYTHON_LIB_PATH"
+        NXT_PYTHON_LDFLAGS="-L$NXT_PYTHON_LIB_PATH -Wl,-rpath,$NXT_PYTHON_LIB_PATH"
     else
         NXT_PYTHON_LDFLAGS=""
     fi