build: Add `double_conversion` package for Linux hosts

A continuation of previous steps wrt #21194 (closed).

Context: https://github.com/bitcoin/bitcoin/pull/24615#issuecomment-1080809879.

Guix builds:

• on x86_64:

db928383b62b6c27a273152381ba859d58f2b20bf806e23bd163c34d916ae48e  guix-build-2a90059993b3/output/aarch64-linux-gnu/SHA256SUMS.part
1937aaa9a6b4ac8e2b6edeabf782ace7225b7abdb7242db546dad2510c139c05  guix-build-2a90059993b3/output/aarch64-linux-gnu/bitcoin-2a90059993b3-aarch64-linux-gnu-debug.tar.gz
6bd972593bf302d1c61928504a8cf299f82d6c643e3c645645233307b1643b4a  guix-build-2a90059993b3/output/aarch64-linux-gnu/bitcoin-2a90059993b3-aarch64-linux-gnu.tar.gz
48ba553b14c47b8cd5334eb4b53b5976d8b6dbd5ea99cc9f1810c98751a84c78  guix-build-2a90059993b3/output/arm-linux-gnueabihf/SHA256SUMS.part
b645e68d72511b0a739c2fcae512f31c6126adb43aa667d9bf325ba224d6fa9e  guix-build-2a90059993b3/output/arm-linux-gnueabihf/bitcoin-2a90059993b3-arm-linux-gnueabihf-debug.tar.gz
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288c5e306996f3dfbc3b4bd2681ec0faaa91e2c61b0bd14eefd0f4a0e8634a06  guix-build-2a90059993b3/output/arm64-apple-darwin/bitcoin-2a90059993b3-arm64-apple-darwin-unsigned.dmg
85c63680ac7fe5a2ac52a400d995817ac7480fb1868fff9484b036f691ce312f  guix-build-2a90059993b3/output/arm64-apple-darwin/bitcoin-2a90059993b3-arm64-apple-darwin-unsigned.tar.gz
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0009ca4894c1e1432456b1e7043546ebd8f1333d8e6c69c1f894ba7023df3cff  guix-build-2a90059993b3/output/powerpc64-linux-gnu/SHA256SUMS.part
b60539f7fd8ff07ac624eac090de86775552e6c58e760b21f0b2164de8c11cb2  guix-build-2a90059993b3/output/powerpc64-linux-gnu/bitcoin-2a90059993b3-powerpc64-linux-gnu-debug.tar.gz
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08a25e57de58b4b7b47b607eefa2da17ded5acdbf4d035af1f2324b7c9d99893  guix-build-2a90059993b3/output/x86_64-apple-darwin/SHA256SUMS.part
363d7fbd3f455743abc6c838ccc3fede7aa2b05d2e393546852f4e1907ac3d60  guix-build-2a90059993b3/output/x86_64-apple-darwin/bitcoin-2a90059993b3-x86_64-apple-darwin-unsigned.dmg
99904773b72e3e0887647ed85e5872124a023f8aa8a78145b39f28103ce00b15  guix-build-2a90059993b3/output/x86_64-apple-darwin/bitcoin-2a90059993b3-x86_64-apple-darwin-unsigned.tar.gz
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bd2517e597ed56097e13f9bfe1f8f3454e505b287af23b2c03ca2dfef32157dd  guix-build-2a90059993b3/output/x86_64-w64-mingw32/SHA256SUMS.part
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• on arm64:

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16bb9b4e714b3cdd1b9639769c933f4a2800d91b059a497eee4d063cf9fa8424  guix-build-2a90059993b3/output/arm64-apple-darwin/SHA256SUMS.part
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7542ae436ecd75f260a181807cd424c0fc0596208332dd9e58e1e48c2fa01638  guix-build-2a90059993b3/output/arm64-apple-darwin/bitcoin-2a90059993b3-arm64-apple-darwin-unsigned.tar.gz
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Please note the diff

--- x86_64	2022-07-19 10:15:31.475389130 +0100
+++ arm64	2022-07-19 10:15:51.387233404 +0100
@@ -1,13 +1,10 @@
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