Add libunwind validation backtrace

[kswiecicki]

Libunwind backtrace can be enabled using cmake option VAL_USE_LIBUNWIND_BACKTRACE, it is set to OFF by default.

Addresses: #368

An example output from backtrace implementation using libunwind looks like this:

<VALIDATION>[ERROR]: (_ZN16validation_layer15RefCountContext14updateRefCountEPvNS0_18RefCountUpdateTypeE+241) [0x7f95f3809731]
<VALIDATION>[ERROR]: (_ZN16validation_layer15RefCountContext14createRefCountEPv+31) [0x7f95f380807f]
<VALIDATION>[ERROR]: (_ZN16validation_layer15urContextCreateEjPKP19ur_device_handle_t_PK23ur_context_properties_tPP20ur_context_handle_t_+190) [0x7f95f380094e]
<VALIDATION>[ERROR]: (urContextCreate+86) [0x7f95f37f3566]
<VALIDATION>[ERROR]: (_ZN64valDeviceTestMultithreaded_testUrContextRetainReleaseLeakMt_Test8TestBodyEv+56) [0x560275107258]
<VALIDATION>[ERROR]: (_ZN7testing8internal38HandleSehExceptionsInMethodIfSupportedINS_4TestEvEET0_PT_MS4_FS3_vEPKc+123) [0x56027516af8b]
<VALIDATION>[ERROR]: (_ZN7testing8internal35HandleExceptionsInMethodIfSupportedINS_4TestEvEET0_PT_MS4_FS3_vEPKc+106) [0x56027514e02a]
<VALIDATION>[ERROR]: (_ZN7testing4Test3RunEv+195) [0x56027512f0e3]
<VALIDATION>[ERROR]: (_ZN7testing8TestInfo3RunEv+304) [0x56027512fc70]
<VALIDATION>[ERROR]: (_ZN7testing9TestSuite3RunEv+317) [0x5602751304bd]
<VALIDATION>[ERROR]: (_ZN7testing8internal12UnitTestImpl11RunAllTestsEv+1108) [0x560275140eb4]
<VALIDATION>[ERROR]: (_ZN7testing8internal38HandleSehExceptionsInMethodIfSupportedINS0_12UnitTestImplEbEET0_PT_MS4_FS3_vEPKc+123) [0x56027516dbeb]
<VALIDATION>[ERROR]: (_ZN7testing8internal35HandleExceptionsInMethodIfSupportedINS0_12UnitTestImplEbEET0_PT_MS4_FS3_vEPKc+106) [0x56027515047a]
<VALIDATION>[ERROR]: (_ZN7testing8UnitTest3RunEv+203) [0x560275140a0b]
<VALIDATION>[ERROR]: (_Z13RUN_ALL_TESTSv+17) [0x5602751192a1]
<VALIDATION>[ERROR]: (main+61) [0x56027511927d]
<VALIDATION>[ERROR]: (__libc_init_first+144) [0x7f95f3261d90]
<VALIDATION>[ERROR]: (__libc_start_main+128) [0x7f95f3261e40]
<VALIDATION>[ERROR]: (_start+37) [0x560275106a05]

[pbalcer]

hm, I think libbacktrace would also give us source code information.

[kswiecicki]

hm, I think libbacktrace would also give us source code information.

I've tested the libbacktrace and it provides more information.
Closed in favor of: #394