Added dependency on SLF4J.

The spec template has been modified to require SLF4J package. The
build script has been modified to include the SLF4J library.

https://pagure.io/jss/issue/7

.classpath

@@ -3,5 +3,6 @@
 	<classpathentry excluding="samples/" kind="src" path=""/>
 	<classpathentry kind="src" path="samples"/>
 	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER"/>
+	<classpathentry kind="lib" path="/usr/share/java/slf4j/slf4j-api.jar"/>
 	<classpathentry kind="output" path="bin"/>
 </classpath>

build_java.pl

@@ -162,8 +162,9 @@ sub setup_vars {
     }
     $jni_header_dir = "$dist_dir/private/jss/_jni";
 
+    $classpath = "-classpath /usr/share/java/slf4j/slf4j-api.jar";
     if( $jce_jar ) {
-        $classpath = "-classpath $jce_jar";
+        $classpath .= ":$jce_jar";
     }
 
     # retrieve present working directory

jss.spec.in

@@ -37,13 +37,21 @@ BuildRequires:  nss-devel >= 3.28.4-6
 BuildRequires:  nspr-devel >= 4.13.1
 BuildRequires:  java-devel
 BuildRequires:  jpackage-utils
+BuildRequires:  slf4j
+%if 0%{?fedora} || 0%{?rhel} > 7
+BuildRequires:  slf4j-jdk14
+%endif
 %if 0%{?fedora} >= 25 || 0%{?rhel} > 7
 BuildRequires:  perl-interpreter
 %endif
 
 Requires:       nss >= 3.28.4-6
 Requires:       java-headless
 Requires:       jpackage-utils
+Requires:       slf4j
+%if 0%{?fedora} || 0%{?rhel} > 7
+Requires:       slf4j-jdk14
+%endif
 
 %description
 Java Security Services (JSS) is a java native interface which provides a bridge