Fix compile error using asm

[Pro]

In function 'xPortGetCoreID':
error: expected ')' before ':' token
:"=r"(id));

It is recommended to use __asm__ instead of asm

See:
https://gcc.gnu.org/onlinedocs/gcc/Alternate-Keywords.html#Alternate-Keywords

[CLAassistant]

All committers have signed the CLA.

[igrr]

Hi @Pro, can you please describe the case in which you get this error? Are you passing any custom CFLAGS when compiling the source files?

[Pro]

I do not know which flag exactly caused the compile error, but I'm using the open62541 library in combination with the ESP32 and it has very strict compile flags.

Is there a specific reason why you would like to use asm instead of __asm__? (Please note the description in the linked documentation)

[projectgus]

I'm guessing @Pro is either compiling some source files in their project with either -ansi or std=c99 or similar, and this file is including FreeRTOS headers.

I don't think there is a downside to us using __asm__ in public headers. Have forwarded this to our internal review queue, if a downside comes up then I'll update this PR.

[projectgus]

Cherry-picked in 1853334, thanks!