fix esp32 builds

[ellensp]

Description

Since f2d585a attempting to build marlin for esp32 based boards under windows results in the error.

'CC' is not recognized as an internal or external command, operable program or batch file.

The issue is

                # Skip '*-elf-g++' (crosstool-NG)
                if not gpath.stem.endswith('-elf-g++'):
                    gccpath = str(gpath.resolve())
                    break

But esp32 uses .platformio/packages/toolchain-xtensa32/bin/xtensa-esp32-elf-g++

Under Linux it defaults back to g++, and most systems have this compiler so it does not error.
But under windows it defaults to CC, and windows does not have a stock compiler installed.

The fix is to also check for esp32, if "xtensa32" is in the path it is a esp32 so don't skip this *-elf-g++

                # Skip '*-elf-g++' (crosstool-NG) except for xtensa32
                if not "xtensa32" not in str(gpath) and gpath.stem.endswith('-elf-g++'):
                    gccpath = str(gpath.resolve())
                    break

Requirements

use a ESP32 based board eg
#define MOTHERBOARD BOARD_MKS_TINYBEE

Benefits

Builds as expected

Related Issues

Build error using mks tinybee board #27553

[thinkyhead]

Good catch, thanks! Is the capitalized "CC" being derived from environment variable $CC or somewhere else?