Fix crash bug when build with libncursesw.so.6 and libtinfow.so.6
The FindCurses.cmake is too old to build with
```-DCURSES_NEED_WIDE=TRUE``` option.
In some latest ENV, always using libncursesw.so.6 and libtinfow.so.6.
The nvtop will crashed with these messages below:
```
AddressSanitizer:DEADLYSIGNAL
=================================================================
==50432==ERROR: AddressSanitizer: SEGV on unknown address 0x0000000000c8 (pc 0x7f9c4d507d39 bp 0x7f9c4d4e6de8 sp 0x7ffc057963a8 T0)
==50432==The signal is caused by a READ memory access.
==50432==Hint: address points to the zero page.
#0 0x7f9c4d507d38 in termattrs_sp (/lib64/libncursesw.so.6+0x1fd38)
#1 0x7f9c4d504f73 in _nc_setupscreen_sp (/lib64/libncursesw.so.6+0x1cf73)
#2 0x7f9c4d50078b in newterm_sp (/lib64/libncursesw.so.6+0x1878b)
#3 0x7f9c4d500c08 in newterm (/lib64/libncursesw.so.6+0x18c08)
#4 0x7f9c4d4fca53 in initscr (/lib64/libncursesw.so.6+0x14a53)
#5 0x55bd7f6d693d in initialize_curses (/usr/local/bin/nvtop+0x5893d)
#6 0x55bd7f6c9f7a in main (/usr/local/bin/nvtop+0x4bf7a)
#7 0x7f9c4c998f1a in __libc_start_main (/lib64/libc.so.6+0x23f1a)
#8 0x55bd7f6ca789 in _start (/usr/local/bin/nvtop+0x4c789)
```
The load library have some problem, NOTE libtinfow.so.6 and
libtinfo.so.6 load at the same time, it is the root cause.
```
ldd /usr/local/bin/nvtop
linux-vdso.so.1 (0x00007ffca6d82000)
libasan.so.5 => /usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/libasan.so.5 (0x00007f8823464000)
libm.so.6 => /lib64/libm.so.6 (0x00007f8823326000)
libnvidia-ml.so.1 => /usr/lib64/libnvidia-ml.so.1 (0x00007f8822d00000)
libncursesw.so.6 => /lib64/libncursesw.so.6 (0x00007f8822cc5000)
libtinfo.so.6 => /lib64/libtinfo.so.6 (0x00007f8822c89000)
libubsan.so.1 => /usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/libubsan.so.1 (0x00007f8822321000)
libc.so.6 => /lib64/libc.so.6 (0x00007f8822152000)
libdl.so.2 => /lib64/libdl.so.2 (0x00007f882214c000)
librt.so.1 => /lib64/librt.so.1 (0x00007f8822142000)
libpthread.so.0 => /lib64/libpthread.so.0 (0x00007f8822120000)
libstdc++.so.6 => /usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/libstdc++.so.6 (0x00007f8821ea8000)
libgcc_s.so.1 => /usr/lib/gcc/x86_64-pc-linux-gnu/9.2.0/libgcc_s.so.1 (0x00007f8821e8e000)
/lib64/ld-linux-x86-64.so.2 (0x00007f8823fc5000)
libtinfow.so.6 => /lib64/libtinfow.so.6 (0x00007f8821e4f000)
```
To fix it, the FindCurses.cmake should using libtinfow.so.6 instead of
libtinfo.so.6 when DCURSES_NEED_WIDE=TRUE. So I updated the
FindCurses.cmake to latest version to fix this problem.
Signed-off-by: Huang Rui <vowstar@gmail.com>
