treewide: *Phase(s)? variables are optional

If these aren't defined, the stdenv defaults are used in the `*Phase`
case, or no extra phases are done, in the `*Phases` case.

pkgs/development/tools/build-managers/cmake/setup-hook.sh

@@ -99,7 +99,7 @@ cmakeConfigurePhase() {
     cmakeFlags="-DCMAKE_FIND_PACKAGE_NO_PACKAGE_REGISTRY=ON $cmakeFlags"
     cmakeFlags="-DCMAKE_FIND_PACKAGE_NO_SYSTEM_PACKAGE_REGISTRY=ON $cmakeFlags"
 
-    if [ "$buildPhase" = ninjaBuildPhase ]; then
+    if [ "${buildPhase-}" = ninjaBuildPhase ]; then
         cmakeFlags="-GNinja $cmakeFlags"
     fi
 
@@ -115,7 +115,7 @@ cmakeConfigurePhase() {
     runHook postConfigure
 }
 
-if [ -z "${dontUseCmakeConfigure-}" -a -z "$configurePhase" ]; then
+if [ -z "${dontUseCmakeConfigure-}" -a -z "${configurePhase-}" ]; then
     setOutputFlags=
     configurePhase=cmakeConfigurePhase
 fi

pkgs/development/tools/build-managers/gn/setup-hook.sh

@@ -9,6 +9,6 @@ gnConfigurePhase() {
     runHook postConfigure
 }
 
-if [ -z "${dontUseGnConfigure-}" -a -z "$configurePhase" ]; then
+if [ -z "${dontUseGnConfigure-}" -a -z "${configurePhase-}" ]; then
     configurePhase=gnConfigurePhase
 fi

pkgs/development/tools/build-managers/meson/setup-hook.sh

@@ -36,7 +36,7 @@ mesonConfigurePhase() {
     runHook postConfigure
 }
 
-if [ -z "${dontUseMesonConfigure-}" -a -z "$configurePhase" ]; then
+if [ -z "${dontUseMesonConfigure-}" -a -z "${configurePhase-}" ]; then
     setOutputFlags=
     configurePhase=mesonConfigurePhase
 fi

pkgs/development/tools/build-managers/ninja/setup-hook.sh

@@ -19,7 +19,7 @@ ninjaBuildPhase() {
     runHook postBuild
 }
 
-if [ -z "${dontUseNinjaBuild-}" -a -z "$buildPhase" ]; then
+if [ -z "${dontUseNinjaBuild-}" -a -z "${buildPhase-}" ]; then
     buildPhase=ninjaBuildPhase
 fi
 
@@ -38,7 +38,7 @@ ninjaInstallPhase() {
     runHook postInstall
 }
 
-if [ -z "${dontUseNinjaInstall-}" -a -z "$installPhase" ]; then
+if [ -z "${dontUseNinjaInstall-}" -a -z "${installPhase-}" ]; then
     installPhase=ninjaInstallPhase
 fi
 
@@ -73,6 +73,6 @@ ninjaCheckPhase() {
     runHook postCheck
 }
 
-if [ -z "${dontUseNinjaCheck-}" -a -z "$checkPhase" ]; then
+if [ -z "${dontUseNinjaCheck-}" -a -z "${checkPhase-}" ]; then
     checkPhase=ninjaCheckPhase
 fi

pkgs/development/tools/build-managers/scons/setup-hook.sh

@@ -71,14 +71,14 @@ sconsCheckPhase() {
     runHook postCheck
 }
 
-if [ -z "$buildPhase" ]; then
+if [ -z "${buildPhase-}" ]; then
     buildPhase=sconsBuildPhase
 fi
 
-if [ -z "${dontUseSconsInstall-}" -a -z "$installPhase" ]; then
+if [ -z "${dontUseSconsInstall-}" -a -z "${installPhase-}" ]; then
     installPhase=sconsInstallPhase
 fi
 
-if [ -z "$checkPhase" ]; then
+if [ -z "${checkPhase-}" ]; then
     checkPhase=sconsCheckPhase
 fi