Disable overriding the dynamic symbols from other libraries

This should allow using both libzstd-jni.so and libzstd.so from the same
process without zstd-jni using functions defined in libzstd.so.

We use a linker flag that affects only ELF platforms. From man ld:

-Bsymbolic

   When creating a shared library, bind references to global symbols to
   the definition within the shared library, if any.  Normally, it is
   possible for a program linked against a shared library to override
   the definition within the shared library.  This option is only
   meaningful on ELF platforms which support shared libraries.

build.sbt

@@ -89,7 +89,7 @@ jniGccFlags := (
   else
     // the default is compilation with GCC
     jniGccFlags.value ++ Seq(
-        "-static-libgcc", "-Wl,--version-script=" + PWD + "/libzstd-jni.so.map")
+        "-static-libgcc", "-Wl,--version-script=" + PWD + "/libzstd-jni.so.map", "-Wl,-Bsymbolic")
   )
 
 // Special case the jni platform header on windows (use the one from the repo)

make_so.sh

@@ -20,7 +20,7 @@ compile () {
         scp -r src/main/native $HOST:
         scp ./libzstd-jni.so.map $HOST:
     fi
-    ssh $HOST 'export PATH=$HOME/bin:$PATH; '$CC' -Wl,--version-script=./libzstd-jni.so.map -shared -flto -fPIC -O3 -DZSTD_LEGACY_SUPPORT=4 -DZSTD_MULTITHREAD=1 -I/usr/include -I./jni -I./native -I./native/common -I./native/legacy -std=c99 -lpthread -o libzstd-jni-'$VERSION'.so native/*.c native/legacy/*.c native/common/*.c native/compress/*.c native/decompress/*.[cS] native/dictBuilder/*.c'
+    ssh $HOST 'export PATH=$HOME/bin:$PATH; '$CC' -Wl,--version-script=./libzstd-jni.so.map -Wl,-Bsymbolic -shared -flto -fPIC -O3 -DZSTD_LEGACY_SUPPORT=4 -DZSTD_MULTITHREAD=1 -I/usr/include -I./jni -I./native -I./native/common -I./native/legacy -std=c99 -lpthread -o libzstd-jni-'$VERSION'.so native/*.c native/legacy/*.c native/common/*.c native/compress/*.c native/decompress/*.[cS] native/dictBuilder/*.c'
     mkdir -p $INSTALL
     scp $HOST:libzstd-jni-$VERSION.so $INSTALL
 }

make_so_cross.sh

@@ -18,7 +18,7 @@ compile() {
     rsync ./libzstd-jni.so.map $BUILD_DIR
 
     pushd $BUILD_DIR
-    $CC -shared -static-libgcc -Wl,--version-script=./libzstd-jni.so.map -fPIC -O3 -flto -DZSTD_LEGACY_SUPPORT=4 -DZSTD_MULTITHREAD=1 -I/usr/include -I./jni -I./native -I./native/common -I./native/legacy -std=c99 -lpthread -o libzstd-jni-$VERSION.so native/*.c native/legacy/*.c native/common/*.c native/compress/*.c native/decompress/*.c native/dictBuilder/*.c
+    $CC -shared -static-libgcc -Wl,--version-script=./libzstd-jni.so.map -Wl,-Bsymbolic -fPIC -O3 -flto -DZSTD_LEGACY_SUPPORT=4 -DZSTD_MULTITHREAD=1 -I/usr/include -I./jni -I./native -I./native/common -I./native/legacy -std=c99 -lpthread -o libzstd-jni-$VERSION.so native/*.c native/legacy/*.c native/common/*.c native/compress/*.c native/decompress/*.c native/dictBuilder/*.c
     popd
 
     mkdir -p $INSTALL

make_so_cross_buster.sh

@@ -18,7 +18,7 @@ compile() {
     rsync ./libzstd-jni.so.map buster:$BUILD_DIR
 
 
-    ssh buster 'cd '$BUILD_DIR'; '$CC' -shared -static-libgcc -Wl,--version-script=./libzstd-jni.so.map -fPIC -O3 -flto -DZSTD_LEGACY_SUPPORT=4 -DZSTD_MULTITHREAD=1 -I/usr/include -I./jni -I./native -I./native/common -I./native/legacy -std=c99 -lpthread -o libzstd-jni-'$VERSION'.so native/*.c native/legacy/*.c native/common/*.c native/compress/*.c native/decompress/*.c native/dictBuilder/*.c'
+    ssh buster 'cd '$BUILD_DIR'; '$CC' -shared -static-libgcc -Wl,--version-script=./libzstd-jni.so.map -Wl,-Bsymbolic -fPIC -O3 -flto -DZSTD_LEGACY_SUPPORT=4 -DZSTD_MULTITHREAD=1 -I/usr/include -I./jni -I./native -I./native/common -I./native/legacy -std=c99 -lpthread -o libzstd-jni-'$VERSION'.so native/*.c native/legacy/*.c native/common/*.c native/compress/*.c native/decompress/*.c native/dictBuilder/*.c'
 
     mkdir -p $INSTALL
     rsync buster:$BUILD_DIR/libzstd-jni-$VERSION.so $INSTALL