qemu_tcg_iret: hash the offset-table keys to shrink the binary

The uname-keyed #DE offset table had grown to 4,873 rows (~392 KiB of
fingerprint strings plus a pointer array), dwarfing the rest of the
component. Key each row on an FNV-1a-64 hash of the trimmed
"<release> <version>" instead of the string -- a packed
{ uint64_t uname_hash; uint32_t de_offset; }, with the readable uname
kept as a trailing // comment. match_de_handler hashes the runtime
fingerprint and linear-scans. Binary: 597 KiB -> 118 KiB, and the string
blob and .data.rel.ro relocations are gone.

The hash function lives in a shared include/kasld/hash.h (reused by the
other uname-keyed components), and tests/check-hash-parity recomputes
every row's key from its uname comment to assert the runtime hash, the
stored key, and per-file distinctness all agree -- so the runtime hash
and the offline generator cannot silently drift.

Author: bcoles

Makefile

@@ -609,6 +609,7 @@ lint :
 	@$(TEST_DIR)/check-component-output
 	@$(TEST_DIR)/check-component-meta
 	@$(TEST_DIR)/check-live-probes
+	@$(TEST_DIR)/check-hash-parity
 	@$(TEST_DIR)/check-text-floor
 	@$(TEST_DIR)/check-text-region
 	@$(TEST_DIR)/check-confidence-floor