core_defines: set TMPDIR to $SRCDIR

There was a bug where proc/10-core_defines.sh set TMPDIR as $SRCDIR,
but then the script sourced etc/autobuild3/ab3_defcfg.sh, which
overrides TMPDIR as /tmp, a tmpfs mount point in systemd-based systems.

This could result in peculiar OOM-like errors during link time, especially
when packages utilise LTO.

Author: MingcongBai

etc/autobuild/ab3_defcfg.sh

@@ -2,7 +2,11 @@
 ##Autobuild default config file
 ##@copyright CC0
 
-##Misc building flags
+# Environmental Settings
+# Avoid setting TMPDIR as tmpfs mount points.
+TMPDIR="$SRCDIR"
+
+# Misc building flags
 ABARCHIVE=autobuild-aoscarchive	# Archive program
 ABSHADOW=yes			# Shall shadow builds be performed by default?
 NOLTO=no			# Enable LTO by default.
@@ -58,11 +62,9 @@ AB_SAN_LEK=0
 AB_LD_BFD=0
 
 ##OS Directory Tree
-# Built-in variables for OS3 directory tree.
+# Built-in variables for AOSC OS directory tree.
 # Will be updated. Therefore not part of conffiles.
 #
-# COPYLEFT TO WHOEVER NEEDS IT.
-#
 PREFIX="/usr"
 BINDIR="/usr/bin"
 LIBDIR="/usr/lib"
@@ -79,7 +81,6 @@ X11CONF="/etc/X11/xorg.conf.d"
 STATDIR="/var"
 INCLUDE="/usr/include"
 BOOTDIR="/boot"
-TMPDIR="/tmp"
 LIBEXEC="/usr/libexec"
 MANDIR="/usr/share/man"
 FDOAPP="/usr/share/applications"

proc/10-core_defines.sh

@@ -6,9 +6,6 @@ export SRCDIR="$PWD"
 export PKGDIR="$PWD/abdist"
 export SYMDIR="$PWD/abdist-dbg"
 
-# Avoid dpkg-deb failure with larger packages on low RAM hosts.
-export TMPDIR="$SRCDIR"
-
 BUILD_START(){ true; }
 BUILD_READY(){ true; }
 BUILD_FINAL(){ true; }