Fixed internal function instrumentation if only pre or post hook is given #116

Job	Run time
build-php-deps / build-php-dependencies	1m 17s
test-sources-license / test-sources-license	5s
build-native / setup-build-matrix / setup-build-matrix	1s
build-native / build-agent-library (linux-x86-64, amd64, deb rpm)	4m 51s
build-native / build-agent-library (linuxmusl-x86-64, amd64, apk)	5m 1s
build-native / build-agent-library (linux-arm64, 1, arm64, deb rpm)	35m 22s
build-native / build-agent-library (linuxmusl-arm64, 1, arm64, apk)	35m 24s
build-packages / setup-build-matrix / setup-build-matrix	1s
tests-phpt / setup-build-matrix / setup-build-matrix	1s
build-packages / build-packages (linux-x86-64, amd64, deb rpm)	54s
build-packages / build-packages (linuxmusl-x86-64, amd64, apk)	27s
build-packages / build-packages (linux-arm64, 1, arm64, deb rpm)	2m 42s
build-packages / build-packages (linuxmusl-arm64, 1, arm64, apk)	31s
tests-phpt / test-phpt (linux-x86-64, amd64, deb rpm)	47s
tests-phpt / test-phpt (linuxmusl-x86-64, amd64, apk)	27s
tests-phpt / test-phpt (linux-arm64, 1, arm64, deb rpm)	2m 13s
tests-phpt / test-phpt (linuxmusl-arm64, 1, arm64, apk)	1m 47s
ci	1s
	1h 31m 52s

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