Adds minimal improvements to build.sh, better cast in JNI

Make output of find go to stderr, add set -e at the start of build.sh script and changes a (jlong) for a reinterpret_cast<jlong> in JNI code

Signed-off-by: ncordon <nacho.cordon.castillo@gmail.com>

build.sh

@@ -10,6 +10,8 @@
 # --native: compiles the native code, with appropriate flags for each system
 # -all: compiles both the native code and the Scala code, in that order
 
+set -e
+
 PROTO_DIR="src/main/proto"
 SDK_MAJOR="v3"
 SDK_VERSION="${SDK_MAJOR}.1.0"
@@ -84,7 +86,7 @@ function getSDKFiles {
 # Checks that the library has been downloaded correctly
 function checkLibuastDownload {
     set -e
-    find src/main/resources
+    find src/main/resources 1>&2
     nm src/main/resources/libuast/libuast${LIBUAST_FMT} | grep -c UastDecode > /dev/null || exit -2
     nm src/main/resources/libuast/libuast${LIBUAST_FMT} | wc -l > /dev/null || exit -2
 }

src/main/native/org_bblfsh_client_v2_libuast_Libuast.cc

@@ -841,7 +841,7 @@ JNIEXPORT jobject JNICALL Java_org_bblfsh_client_v2_Context_nativeEncode(
 JNIEXPORT jlong JNICALL
 Java_org_bblfsh_client_v2_Context_00024_create(JNIEnv *env, jobject self) {
   Context *c = new Context();
-  return (jlong) c;
+  return reinterpret_cast<jlong>(c);
 }
 
 JNIEXPORT void JNICALL Java_org_bblfsh_client_v2_Context_dispose(JNIEnv *env,