Open link-verifier target files with encoding="utf8", errors='ignore' options

[paulbartell]

• Open link-verifier target files with encoding="utf8", errors='ignore' options
• Print each file path that is processed to stdout for debugging purposes.

[paulbartell]

@aggarw13 here's a link to the file which triggered this issue: https://github.com/FreeRTOS/FreeRTOS-Kernel/blob/ac2c383bc14b2577101cad238c8779f4d9c14d6c/portable/GCC/ARM7_AT91SAM7S/lib_AT91SAM7X256.h#L1469

Specifically, the "µ" character in "µsecond".

[paulbartell]

To add some additional background:
Bytes from 0x80 to 0xBF are invalid starting bytes in UTF-8, however they are valid in other character sets. Some vendor code uses other fixed-width 8-bit character sets with valid characters in the range of 0x80 to 0xBF. This change drops those characters silently.