[Packaging] Add libunwind-devel and libdwarf-devel to build requires

When they are missing, rpmbuild complains as follows:

<stdin>:1:31: fatal error: android/api-level.h: No such file or directory
compilation terminated.
    CHK libelf
    CHK libdw
/usr/lib/gcc/x86_64-redhat-linux/4.7.2/../../../../lib64/crt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
collect2: error: ld returned 1 exit status
Makefile:584: No libdw.h found or old libdw.h found or elfutils is older than 0.138, disables dwarf support. Please install new elfutils-devel/libdw-dev
    CHK libunwind
<stdin>:1:23: fatal error: libunwind.h: No such file or directory
compilation terminated.
Makefile:605: No libunwind found, disabling post unwind support. Please install libunwind-dev[el] >= 0.99