8370659: [mobile] enable static-libs-image for Android

[johanvos]

This PR adds the changes required to compile libjvm.a and the classlibs using the latest upstream code.

Some notes:

To configure/make, the following configuration is recommended:

bash ./configure \
--disable-warnings-as-errors \
--openjdk-target=aarch64-linux-android \
--with-boot-jdk=/opt/jdk-25 \
--with-toolchain-path=/opt/android-ndk-r29/toolchains/llvm/prebuilt/linux-x86_64/bin \
--with-sysroot=/opt/android-ndk-r29/toolchains/llvm/prebuilt/linux-x86_64/sysroot \
--with-toolchain-type=clang

After configuring the build, run
make static-libs-image

Note that this requires Android NDK 29, which can be downloaded from https://developer.android.com/ndk/downloads
I only tested this using Linux. Mac/Windows builds may or may not work.

In make/autoconf/flags-cflags.m4, the minimum android version is set to 32 (-target aarch64-linux-android32). The reason for this is that this version comes with a version of bionic that supports thr_current. This is not strictly needed, but lower versions would require more bionic-specific patches.

I use #ifdef __BIONIC__ and similar in most places where we do "Android" specific checks. The reason for this is that those checks mainly refer to support that is (or isn't) available in Bionic. As such, it is better to compare e.g. bionic with musl and libc unless we are specifically using Android API's

I can provide a sample with a Makefile that validates the build on a real phone, but I think that is not in scope of this PR.

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue

Issue

• JDK-8370659: [mobile] enable static-libs-image for Android (Enhancement - P4)

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/mobile.git pull/40/head:pull/40
$ git checkout pull/40

Update a local copy of the PR:
$ git checkout pull/40
$ git pull https://git.openjdk.org/mobile.git pull/40/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 40

View PR using the GUI difftool:
$ git pr show -t 40

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/mobile/pull/40.diff

Using Webrev

Link to Webrev Comment

[bridgekeeper]

👋 Welcome back jvos! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[mlbridge]

Webrevs

• 00: Full (f7b2b4b5)

[johanvos]

I added a sample that describes how to use the resulting OpenJDK to create and run a HelloJava application directly on a phone: https://github.com/openjdk-mobile/android-tools/tree/main/samples/adbhelloworld