getdeps: restructure bison+flex dependencies

Summary:
We've been squeaking by with assuming that flex is installed already
on posix systems, but that isn't the case on the github actions default
configuration.

Adjust the bison recipe: on windows it deploys both flex and bison.  We use the
same source for both flex and bison but install flex to a separate install
prefix to make it easier to consume the flex dependency distinct from the bison
dependency.

The latest flex release segfaults during compilation on linux unless we
force -DGNU_SOURCE, so the manifest does that on linux.

Reviewed By: simpkins

Differential Revision: D17385051

fbshipit-source-id: 9f31b07849af9de50099d1b20bedba517bbbdf2f

build/fbcode_builder/manifests/bison

@@ -19,4 +19,3 @@ builder = nop
 [install.files.os=windows]
 data = bin/data
 win_bison.exe = bin/bison.exe
-win_flex.exe = bin/flex.exe

build/fbcode_builder/manifests/fbthrift

@@ -11,6 +11,8 @@ repo_url = https://github.com/facebook/fbthrift.git
 builder = cmake
 
 [dependencies]
+bison
+flex
 folly
 wangle
 rsocket-cpp
@@ -20,9 +22,6 @@ libsodium
 googletest
 zstd
 
-[dependencies.any(os=windows, os=darwin)]
-bison
-
 [cmake.defines.test=on]
 BUILD_TESTS=ON
 

build/fbcode_builder/manifests/flex

+[manifest]
+name = flex
+
+[download.not(os=windows)]
+url = https://github.com/westes/flex/releases/download/v2.6.4/flex-2.6.4.tar.gz
+sha256 = e87aae032bf07c26f85ac0ed3250998c37621d95f8bd748b31f15b33c45ee995
+
+[download.os=windows]
+url = https://github.com/lexxmark/winflexbison/releases/download/v2.5.17/winflexbison-2.5.17.zip
+sha256 = 3dc27a16c21b717bcc5de8590b564d4392a0b8577170c058729d067d95ded825
+
+[build.not(os=windows)]
+builder = autoconf
+subdir = flex-2.6.4
+
+[build.os=windows]
+builder = nop
+
+[install.files.os=windows]
+data = bin/data
+win_flex.exe = bin/flex.exe
+
+# Moral equivalent to this PR that fixes a crash when bootstrapping flex
+# on linux: https://github.com/easybuilders/easybuild-easyconfigs/pull/5792
+[autoconf.args.os=linux]
+CFLAGS=-D_GNU_SOURCE