pkg/rocksdb: fix download address

fix the following issue:
```
./db/version_edit.h:76:8: error: implicitly-declared ‘constexpr rocksdb::FileDescriptor::FileDescriptor(const rocksdb::FileDescriptor&)’ is deprecated [-Werror=deprecated-copy]
   76 | struct FileMetaData {
      |        ^~~~~~~~~~~~
./db/version_edit.h:47:19: note: because ‘rocksdb::FileDescriptor’ has user-provided ‘rocksdb::FileDescriptor& rocksdb::FileDescriptor::operator=(const rocksdb::FileDescriptor&)’
   47 |   FileDescriptor& operator=(const FileDescriptor& fd) {
      |                   ^~~~~~~~
In file included from /usr/include/c++/9/bits/stl_algobase.h:64,
                 from /usr/include/c++/9/bits/char_traits.h:39,
                 from /usr/include/c++/9/string:40,
                 from ./db/builder.h:9,
                 from db/builder.cc:10:
/usr/include/c++/9/bits/stl_pair.h:312:51: note: synthesized method ‘rocksdb::FileMetaData::FileMetaData(const rocksdb::FileMetaData&)’ first required here
  312 |        : first(std::forward<_U1>(__x)), second(__y) { }
      |                                                   ^
cc1plus: all warnings being treated as errors
make[1]: *** [Makefile:1892: db/builder.o] Error 1
make[1]: Leaving directory '/root/lkp-tests/tmp-pkg/rocksdb/src/rocksdb-5.15.10'
```
The community has sent a patch to fix this problem(facebook/rocksdb#5553), but there is no release corresponding version, so download the code of the main branch first.

Signed-off-by: Zhou Hao <[email protected]>
Signed-off-by: Philip Li <[email protected]>

pkg/rocksdb/PKGBUILD

@@ -1,26 +1,26 @@
 pkgname=rocksdb
-pkgver=5.15.10
+pkgver=git
 pkgrel=1
 pkgdesc='Embedded key-value store for fast storage'
 arch=(i686 x86_64)
 url='http://rocksdb.org'
 license=(Apache leveldb)
 depends=()
-source=(https://github.com/facebook/rocksdb/archive/v$pkgver.zip)
+source=(https://github.com/facebook/rocksdb.git)
 md5sums=('SKIP')
 
 prepare() {
-  cd rocksdb-$pkgver
+  cd rocksdb
   sed -e 's/\bpython\b/python2/' -i Makefile
 }
 
 build() {
-  cd rocksdb-$pkgver
+  cd rocksdb
   make release
 }
 
 package() {
-  cd rocksdb-$pkgver
+  cd rocksdb
   install -d "$pkgdir"/usr/share/rocksdb
   rm tools/*.o
   rm tools/*.d