Use pkg-config to discover OpenSSL

All supported versions of OpenSSL have pkg-config files.

common/Makefile.am

@@ -18,6 +18,8 @@ AM_CPPFLAGS = \
   -DXRDP_PID_PATH=\"${localstatedir}/run\" \
   -DXRDP_LOG_PATH=\"${localstatedir}/log\"
 
+AM_CFLAGS = $(OPENSSL_CFLAGS)
+
 module_LTLIBRARIES = \
   libcommon.la
 
@@ -50,7 +52,6 @@ libcommon_la_SOURCES = \
   $(PIXMAN_SOURCES)
 
 libcommon_la_LIBADD = \
-  -lcrypto \
-  -lssl \
   -lpthread \
+  $(OPENSSL_LIBS) \
   $(DLOPEN_LIBS)

configure.ac

@@ -125,9 +125,8 @@ AC_CHECK_FUNC(dlopen, [],
 AC_SUBST(DLOPEN_LIBS)
 
 # checking for openssl
-AC_CHECK_HEADER([openssl/rc4.h], [],
-  [AC_MSG_ERROR([please install libssl-dev or openssl-devel])],
-  [#include <stdlib.h>])
+PKG_CHECK_MODULES([OPENSSL], [openssl >= 0], [],
+  [AC_MSG_ERROR([please install libssl-dev or openssl-devel])])
 
 # checking for pam variation
 # Linux-PAM is used in Linux systems