Generate a .sym report for rekkrunchy

[laurentlb]

The rekkrunchy compression tool can show a report and show how the space in the binary is used after compression. If we generate a .sym file, rekkrunchy could give compression details about parts of the shader (e.g. the size of each function).

https://github.com/ConspiracyHu/rekkrunchy-with-analytics
https://github.com/ConspiracyHu/kkpView-public

4 bytes: FOURCC: 'PHXP'
ASCIIZ string: name of the "main" symbol in the binary, which is being described in more detail by this sym file.
4 bytes: data size (Ds) of the main symbol.
4 bytes: count (Sc) of the "detail" symbols that will be used to describe the main symbol.
For each detail symbol (Sc)
    ASCIIZ string: name of the detail symbol, with '::' understood as a separator for folder structure.
For each byte in the main symbol (Ds)
    2 bytes: index of the detail symbol in the above list, that this byte of the main symbol counts as representing.