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

[Johan Vos]

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.

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Commit messages:
 - Changes required to compile libjvm.a and the classlibs using the latest upstream code.

Changes: https://git.openjdk.org/mobile/pull/40/files
  Webrev: https://webrevs.openjdk.org/?repo=mobile&pr=40&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8370659
  Stats: 69 lines in 11 files changed: 66 ins; 0 del; 3 mod
  Patch: https://git.openjdk.org/mobile/pull/40.diff
  Fetch: git fetch https://git.openjdk.org/mobile.git pull/40/head:pull/40

PR: https://git.openjdk.org/mobile/pull/40