Fix inconsistent optimization flags; single source of truth.

depends/hosts/linux.mk

@@ -1,7 +1,7 @@
 linux_CFLAGS=-pipe
 linux_CXXFLAGS=$(linux_CFLAGS)
 
-linux_release_CFLAGS=-O2
+linux_release_CFLAGS=-O1
 linux_release_CXXFLAGS=$(linux_release_CFLAGS)
 
 linux_debug_CFLAGS=-O1

zcutil/build.sh

@@ -37,5 +37,5 @@ PREFIX="$(pwd)/depends/x86_64-unknown-linux-gnu/"
 
 make "$@" -C ./depends/ V=1 NO_QT=1
 ./autogen.sh
-./configure --prefix="${PREFIX}" --with-gui=no "$HARDENING_ARG" "$LCOV_ARG" CXXFLAGS='-Wno-deprecated-declarations -Wno-placement-new -Wno-terminate -Werror -O1 -g'
+./configure --prefix="${PREFIX}" --with-gui=no "$HARDENING_ARG" "$LCOV_ARG" CXXFLAGS='-Wno-deprecated-declarations -Wno-placement-new -Wno-terminate -Werror -g'
 make "$@" V=1