devenum/tests: Skip test if no video capture device is present.
This patch copies the same skip seen in qcap/tests/videocapture.c.
This is to avoid the test crashing with wine and windows.
Followup to 9f3ca141.
ASan crash report
=================================================================
==devenum_test.exe==472==ERROR: AddressSanitizer: access-violation on unknown address 0x000000000000 (pc 0x0001400098c3 bp 0x7ffffe1ffa50 sp 0x7ffffe1ffa30 T0)
==devenum_test.exe==472==The signal is caused by a READ memory access.
==devenum_test.exe==472==Hint: address points to the zero page.
#0 0x0001400098c2 in IEnumMoniker_Next Z:\builds\bernhardu\wine\build64\include\objidl.h:6841
#1 0x0001400094c5 in test_video_input Z:\builds\bernhardu\wine\build64\..\dlls\devenum\tests\devenum.c:1173
#2 0x0001400010d0 in func_devenum Z:\builds\bernhardu\wine\build64\..\dlls\devenum\tests\devenum.c:1224
#3 0x00014000e4d2 in run_test+0x102 (C:\users\gitlab\AppData\Local\Temp\wct\devenum_test.exe+0x14000e4d2)
#4 0x00014000df4c in main+0x4bc (C:\users\gitlab\AppData\Local\Temp\wct\devenum_test.exe+0x14000df4c)
#5 0x00014001006a in mainCRTStartup Z:\builds\bernhardu\wine\build64\..\dlls\msvcrt\crt_main.c:62
#6 0x6fffffc37a64 (C:\windows\system32\kernel32.dll+0x178027a64)
#7 0x6fffffdc08b6 (C:\windows\system32\ntdll.dll+0x1700508b6)
==devenum_test.exe==472==Register values:
rax = 0 rbx = 7ffffe1ffb80 rcx = 0 rdx = 140100000
rdi = 7ffffe1ffaa0 rsi = 1 rbp = 7ffffe1ffa50 rsp = 7ffffe1ffa30
r8 = 7ffffe1ffae0 r9 = 0 r10 = 8 r11 = 202
r12 = 140100000 r13 = fffffc3ff90 r14 = 7ffffe1ffae0 r15 = 0
AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: access-violation Z:\builds\bernhardu\wine\build64\include\objidl.h:6841 in IEnumMoniker_Next
==devenum_test.exe==472==ABORTING