Optimize _apkcerts_write_line

Emit 1 echo command per line instead of 2-4. The build was failing
due to the large number of commands, although I'm surprised because I
thought there was no limit on the size of the commands if they were
in a bash script file.

Bug: 378007883
Test: m out/target/product/vsoc_x86_64_only/obj/PACKAGING/apkcerts_intermediates/aosp_cf_x86_64_only_phone-apkcerts.txt
Change-Id: I29ee8a80c07e47db05e1bb3189a9786425560e9f
diff --git a/core/Makefile b/core/Makefile
index 80eaf2c..eaa9f5f 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -768,10 +768,7 @@
 # $5 partition tag
 # $6 output file
 define _apkcerts_write_line
-$(hide) echo -n 'name="$(1).apk" certificate="$2" private_key="$3"' >> $6
-$(if $(4), $(hide) echo -n ' compressed="$4"' >> $6)
-$(if $(5), $(hide) echo -n ' partition="$5"' >> $6)
-$(hide) echo '' >> $6
+$(hide) echo 'name="$(1).apk" certificate="$2" private_key="$3"$(if $(4), compressed="$4")$(if $(5), partition="$5")' >> $6
 
 endef