Add explicit interpreter invocation of nvram_map_gen.sh

[landon_landonf.org]

Summary

This fixes builds where the source tree is mounted noexec

Test Plan

• Add bhndbus to kernel config
• Mount source tree noexec
• Verify that a clean build completes successfully (both kernel and modules)
• Verify the generated tool output is correct

[emaste]

sys/dev/bhnd/tools/nvram_map_gen.sh

10–12 ↗

(On Diff #16156)

Instead of this you can just use ${AWK:-/usr/bin/awk}

[landon_landonf.org]

• Merge branch 'master' into arcpatch-D6312
• Drop sh accidentally added in master to the dependency lines in sys/conf/files.
• Adopt AWK:- default value syntax recommended by emaste.

[landon_landonf.org]

Thanks; fixed and rebased against HEAD.