RFR: 8261109: [macOS] Remove disabled warning for JNF in make/autoconf/flags-cflags.m4 [v2]

[Phil Race]

> remove un-needed disabling now JNF has gone ..

Phil Race has updated the pull request incrementally with one additional commit since the last revision:

  Remove condition that should have been fixed as part of 8257858

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Changes:
  - all: https://git.openjdk.java.net/jdk/pull/2396/files
  - new: https://git.openjdk.java.net/jdk/pull/2396/files/34dcbfb1..93fd193f

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jdk&pr=2396&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jdk&pr=2396&range=00-01

  Stats: 3 lines in 1 file changed: 0 ins; 3 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2396.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2396/head:pull/2396

PR: https://git.openjdk.java.net/jdk/pull/2396