[Bug 1739392] [NEW] [aarch64] wrong symbol address

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Public bug reported:

gcc-aarch64-linux-gnu package in bionic has gcc version 7.2.0.

I have a bug with relocation symbols in this version.
It seems to be fixed in gcc version 7.2.1 (tested with gcc-linaro-7.2.1-2017.11 
toolchain). Could you please update the package?

Thank you!

Test case:
``` test.c
struct ld_symbol;
extern struct ld_symbol _test_start, _test_end;

unsigned long long test(void)
{
    unsigned long long test_start = (unsigned long long)&_test_start;
    unsigned long long test_end = (unsigned long long)&_test_end;
    return test_end - test_start;
}
```

``` script.ld
OUTPUT_ARCH(aarch64)
OUTPUT_FORMAT(elf64-littleaarch64)
SECTIONS
{
    _test_start = .;
    .text :
    {
        *(.text)
    }
    _test_end = .;
    . += 0xFFFF0000;
}
```

Compile with:
```
aarch64-linux-gnu-gcc -O1 -c test.c -o test.o
aarch64-linux-gnu-objdump -ld test.o
aarch64-linux-gnu-ld -o test.elf -nostdlib --script script.ld --entry test 
test.o
aarch64-linux-gnu-objdump -ld test.elf
```

Bad (current):
```
test.o:
test():
   0:   90000001        adrp    x1, 0 <_test_end>
   4:   f9400021        ldr     x1, [x1]
   8:   90000000        adrp    x0, 0 <_test_start>
   c:   f9400000        ldr     x0, [x0]
  10:   cb000020        sub     x0, x1, x0
  14:   d65f03c0        ret

test.elf:
test(): 
   0:   907fff81        adrp    x1, ffff0000 <_test_end+0xfffeffe8> 
   4:   f9401421        ldr     x1, [x1, #40] 
   8:   907fff80        adrp    x0, ffff0000 <_test_end+0xfffeffe8> 
   c:   f9401000        ldr     x0, [x0, #32] 
  10:   cb000020        sub     x0, x1, x0 
  14:   d65f03c0        ret
```

Good:
```
test():
   0:   90000001        adrp    x1, 0 <_test_end>
   4:   91000021        add     x1, x1, #0x0
   8:   90000000        adrp    x0, 0 <_test_start>
   c:   91000000        add     x0, x0, #0x0
  10:   cb000020        sub     x0, x1, x0
  14:   d65f03c0        ret
```

** Affects: gcc-defaults (Ubuntu)
     Importance: Undecided
         Status: New

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Title:
  [aarch64] wrong symbol address

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