Merge #20644: Add patch to make codesign_allocate compatible with Apple's

a4118c6e20 Add patch to make codesign_allocate compatible with Apple's (Pieter Wuille)

Pull request description:

  This is an alternative to #20638.

  The problem is that Apple's codesign(_allocate) apparently rounds the "vmsize" attribute on the __LINKEDIT section to a multiple of 0x2000 on x86_64 rather than 0x1000 (as their published source code does). This divergence means that the binary signed by codesign is slightly different from the one recreated by our reattach-sig-to-gitian-output process, and the signature being invalid.

  This fixes it by patching our codesign_allocate source code to also use 0x2000. In tests, this appears to result in matching binaries.

ACKs for top commit:
  jonasschnelli:
    Tested ACK a4118c6e20 - removed the osx cache, built commit a4118c6e20 for osx in gitian (dependency where built, patch was applied), signed on my signing mac (detach-sig-create), ran gitian osx signer with the produces signature and the a4118c6e20 build (detach-sig-apply), signature then was successful verified on my Mac (codesign -v /Volumes/Bitcoin-Core/Bitcoin-Qt.app)
  MarcoFalke:
    Concept ACK a4118c6e20

Tree-SHA512: 07b8cdf8216249ddfe4bd38b39f2b48b2e190d4002b84d8981e62197bbbc9f25ac5c137bcc32057b23fbf38cbb2889ef95101ce008edfbf608cd170b88b3acbc

depends/patches/native_cctools/segalign.patch

@@ -0,0 +1,19 @@
+commit 7f2eb11ce6ebec7eb9b8e1429535e453054143e5
+Author: Pieter Wuille <pieter@wuille.net>
+Date:   Sun Dec 13 11:34:21 2020 -0800
+
+    Make cctools_port's codesign_allocate compatible with Apple's
+
+diff --git a/cctools/libstuff/arch.c b/cctools/libstuff/arch.c
+index 6f2332f..d85c25c 100644
+--- a/cctools/libstuff/arch.c
++++ b/cctools/libstuff/arch.c
+@@ -134,7 +134,7 @@ static const struct cpu_entry cpu_entries[] = {
+     { CPU_TYPE_ARM,	    LITTLE_ENDIAN_BYTE_SEX, 0,		       0x4000 },
+     
+     /* desktop */
+-    { CPU_TYPE_X86_64,	    LITTLE_ENDIAN_BYTE_SEX, 0x7fff5fc00000LL,  0x1000 },
++    { CPU_TYPE_X86_64,	    LITTLE_ENDIAN_BYTE_SEX, 0x7fff5fc00000LL,  0x2000 /* Used to be 0x1000; changed to 0x2000 to match Apple's distributed codesign_allocate. */},
+     { CPU_TYPE_I386,	    LITTLE_ENDIAN_BYTE_SEX, 0xc0000000,        0x1000 },
+     { CPU_TYPE_POWERPC,	    BIG_ENDIAN_BYTE_SEX,    0xc0000000,	       0x1000 },
+     { CPU_TYPE_POWERPC64,   BIG_ENDIAN_BYTE_SEX,    0x7ffff00000000LL, 0x1000 },