Unset envsetup.sh variables inside build

Using ANDROID_BUILD_TOP and other envsetup.sh varialbes is already
forbidden in makefiles, but some tools run by the build (like
hidl-gen) will use it if it is set.  Since they are set by envsetup.sh,
and sourcing envsetup.sh before building is optional, unset them inside
the build to get consistent behavior.

Bug: 79250545
Test: m checkbuild
Change-Id: I3e7d9f01390ccdc34c49115f2f15cd7542d9974b
diff --git a/ui/build/config.go b/ui/build/config.go
index d0378ec..1f7656e 100644
--- a/ui/build/config.go
+++ b/ui/build/config.go
@@ -118,6 +118,18 @@
 
 		// Set in envsetup.sh, reset in makefiles
 		"ANDROID_JAVA_TOOLCHAIN",
+
+		// Set by envsetup.sh, but shouldn't be used inside the build because envsetup.sh is optional
+		"ANDROID_BUILD_TOP",
+		"ANDROID_HOST_OUT",
+		"ANDROID_PRODUCT_OUT",
+		"ANDROID_HOST_OUT_TESTCASES",
+		"ANDROID_TARGET_OUT_TESTCASES",
+		"ANDROID_TOOLCHAIN",
+		"ANDROID_TOOLCHAIN_2ND_ARCH",
+		"ANDROID_DEV_SCRIPTS",
+		"ANDROID_EMULATOR_PREBUILTS",
+		"ANDROID_PRE_BUILD_PATHS",
 	)
 
 	// Tell python not to spam the source tree with .pyc files.