Update libfuzzer to LLVM 18 #983

Job	Run time
Test (bloaty_fuzz_target)	21m 31s
Test (bloaty_fuzz_target_52948c)	24m 52s
Test (curl_curl_fuzzer_http)	23m 18s
Test (freetype2_ftfuzzer)	15m 12s
Test (harfbuzz_hb-shape-fuzzer)	19m 12s
Test (harfbuzz_hb-shape-fuzzer_17863b)	18m 49s
Test (jsoncpp_jsoncpp_fuzzer)	12m 50s
Test (lcms_cms_transform_fuzzer)	13m 44s
Test (libjpeg-turbo_libjpeg_turbo_fuzzer)	13m 12s
Test (libpcap_fuzz_both)	13m 26s
Test (libpng_libpng_read_fuzzer)	13m 3s
Test (libxml2_xml)	13m 7s
Test (libxml2_xml_e85b9b)	13m 43s
Test (libxslt_xpath)	14m 35s
Test (mbedtls_fuzz_dtlsclient)	14m 29s
Test (mbedtls_fuzz_dtlsclient_7c6b0e)	15m 2s
Test (openh264_decoder_fuzzer)	12m 44s
Test (openssl_x509)	17m 6s
Test (openthread_ot-ip6-send-fuzzer)	14m 2s
Test (php_php-fuzz-parser_0dbedb)	28m 20s
Test (proj4_proj_crs_to_crs_fuzzer)	21m 48s
Test (re2_fuzzer)	13m 18s
Test (sqlite3_ossfuzz)	15m 32s
Test (stb_stbi_read_fuzzer)	12m 22s
Test (systemd_fuzz-link-parser)	17m 49s
Test (vorbis_decode_fuzzer)	13m 22s
Test (woff2_convert_woff2ttf_fuzzer)	13m 26s
Test (zlib_zlib_uncompress_fuzzer)	12m 41s
	7h 32m 35s

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