package/acpitool: needs threads, shared; unavailable for bfin

package/acpitool: needs threads, shared; unavailable for bfin

acpitool requires threads.

However, it does not check for threads in its configure script, so
forgets to link with -pthreads, so fails to build in static-only
scenarii.

However, upstream has been dead for the past 7+ years now, so there is
not much point trying to fix this. Besides, a system with ACPI is most
probably a biggish system, so shared libs will probably be enabled, so
we just require shared libs.

As for bfin, the cryptic configure failure:
    configure: error: C++ compiler cannot create executables

is due to the order in which AC_PROG_CXX and AC_PROG_CC are called.
Calling AC_PROG_CC first fixes this error message in this specific case.
However, this is a toolchain issue, as this does not occur for other
toolchains.

Still, inverting the call would anyway then cause linking errors:

    /home/ymorin/dev/buildroot/O/host/usr/bin/bfin-linux-g++  -D_LARGEFILE_SOURCE -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64  -Os    -o acpitool main.o acpitool.o ac_adapter.o toshiba.o asus.o thinkpad.o cpu.o battery.o freq.o -lgcc
    acpitool.o: In function `Has_ACPI(char*)':
    acpitool.cpp:(.text+0x1be): undefined reference to `_Unwind_Resume'
    acpitool.o: In function `Get_Kernel_Version(char*, int)':
    acpitool.cpp:(.text+0x2aa): undefined reference to `_Unwind_Resume'
    acpitool.o: In function `Set_Kernel_Version()':
    acpitool.cpp:(.text+0x43e): undefined reference to `_Unwind_Resume'
    acpitool.o: In function `Do_Fan_Info(int)':
    acpitool.cpp:(.text+0x60a): undefined reference to `_Unwind_Resume'
    acpitool.o: In function `Show_WakeUp_Devices(int)':
    acpitool.cpp:(.text+0x770): undefined reference to `_Unwind_Resume'
    acpitool.o:acpitool.cpp:(.text+0x9ca): more undefined references to `_Unwind_Resume' follow
    /home/ymorin/dev/buildroot/O/host/opt/ext-toolchain/bin/../lib/gcc/bfin-buildroot-linux-uclibc/6.1.0/../../../../bfin-buildroot-linux-uclibc/bin/ld: acpitool: hidden symbol `___udivsi3' in /home/ymorin/dev/buildroot/O/host/opt/ext-toolchain/bin/../lib/gcc/bfin-buildroot-linux-uclibc/6.1.0/libgcc.a(_udivsi3.o) is referenced by DSO
    /home/ymorin/dev/buildroot/O/host/opt/ext-toolchain/bin/../lib/gcc/bfin-buildroot-linux-uclibc/6.1.0/../../../../bfin-buildroot-linux-uclibc/bin/ld: final link failed: Bad value
    collect2: error: ld returned 1 exit status

Again, because upstream is dead, there's not much point trying to fix
this... And since there's not many chances that a bfin board has ACPI,
we just disable acpitool for bfin.

Fixes various build failures:
    http://autobuild.buildroot.org/results/6fc/6fc568228b7c5c5be9e35aae73fb09b431896325/
    http://autobuild.buildroot.org/results/f1e/f1eb711123c2d8aea8399b8984a007afec4f65fb/
    http://autobuild.buildroot.org/results/70e/70eb7d7ed93a122b4c7a9890877e721b8d777b00/
    [...]

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Erico Nunes <nunes.erico@gmail.com>
Cc: Peter Korsgaard <peter@korsgaard.com>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>