T7755: Add clang dependency to build hsflowd

[asklymenko]

Change summary

The Clang compiler is required to build the hsflowd package. It will be added as a dependency of the hsflowd package only.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Code style update (formatting, renaming)
• Refactoring (no functional changes)
• Migration from an old Vyatta component to vyos-1x, please link to related PR inside obsoleted component
• Other (please describe): Add dependency to package

Related Task(s)

https://vyos.dev/T7755

Related PR(s)

Checklist:

• I have read the CONTRIBUTING document
• I have linked this PR to one or more Phabricator Task(s)
• My commit headlines contain a valid Task id
• My change requires a change to the documentation
• I have updated the documentation accordingly

[github-actions]

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No issues in PR Title / Commit Title

[sever-sever]

Fixes build hsflowd
Before fix

clang -std=gnu99 -I. -I../json -I../sflow  -fPIC -g -O2 -D_GNU_SOURCE -DHSP_VERSION=2.1.14 -DPROCFS=/proc -DSYSFS=/sys -DETCFS=/etc -DVARFS=/var -DUTHEAP -DHSP_OPTICAL_STATS -DHSP_MOD_DIR=/etc/hsflowd/modules -Wall -Wstrict-prototypes -Wunused-value -Wunused-function   -DSFL_USE_SFDG -DSFL_USE_32BIT_INDEX -c mod_json.c 
make[1]: clang: No such file or directory
make[1]: *** [Makefile:498: mod_json.o] Error 127
make[1]: Leaving directory '/vyos/work/tmp/vpp-ipsec-fix/vyos-build/scripts/package-build/hsflowd/host-sflow/src/Linux'
make: *** [Makefile:16: hsflowd] Error 2
Failed to build package host-sflow: Command 'make deb FEATURES='PCAP DROPMON DBUS PSAMPLE VPP'' returned non-zero exit status 2.
I: Cleaned up build dependency packages