[BUG REPORT] arch/x86/include/asm/uaccess_64.h:119: Error: junk at end of line

[Jingbo Xu]

Hi,

My container failed to compile the latest v6.3, and bisecting shows that
commit 5d1dd961e74334a2178264193ea813d44ce5e725 ("x86/alternatives: Add
alt_instr.flags") introduces the regression.

```
./arch/x86/include/asm/uaccess_64.h:124: Error: found 'L', expected: ')'
./arch/x86/include/asm/uaccess_64.h:124: Error: found 'L', expected: ')'
./arch/x86/include/asm/uaccess_64.h:124: Error: found 'L', expected: ')'
./arch/x86/include/asm/uaccess_64.h:124: Error: found 'L', expected: ')'
./arch/x86/include/asm/uaccess_64.h:124: Error: found 'L', expected: ')'
./arch/x86/include/asm/uaccess_64.h:124: Error: found 'L', expected: ')'
./arch/x86/include/asm/uaccess_64.h:124: Error: junk at end of line,
first unrecognized character is `L'
```

The gcc inside container is:

	gcc (GCC) 6.5.1 20181026 (Alibaba 6.5.1-1)


While the gcc on the host can compile it successfully:
	
	gcc (GCC) 9.2.1 20200522 (Alibaba 9.2.1-3 2.17)


-- 
Thanks,
Jingbo