Allow exporting secret keys.

Requests the passphrase with a popup.

As from GPGME 1.15.0, the loopback pinentry is functional when exporting secret keys. It works fine when the exact passphrase is provided. If it's a wrong passphrase, GPGME does not generate an ::Error, but the app crashes with 'free(): double free detected in tcache 2'.

Hence, this patch cannot be committed to master.

Status : dangerous
Result : works and works not
Reason : a wrong passphrase means a crash

nbproject/Makefile-Debug.mk

@@ -47,6 +47,7 @@ OBJECTFILES= \
 	${OBJECTDIR}/PopupCreate.o \
 	${OBJECTDIR}/PopupDeleter.o \
 	${OBJECTDIR}/PopupExpiryTime.o \
+	${OBJECTDIR}/PopupExportSecretKey.o \
 	${OBJECTDIR}/PopupUploader.o \
 	${OBJECTDIR}/SensitiveTreeTableNodeText.o \
 	${OBJECTDIR}/Tools.o \
@@ -138,6 +139,11 @@ ${OBJECTDIR}/PopupExpiryTime.o: PopupExpiryTime.cpp
 	${RM} "$@.d"
 	$(COMPILE.cc) -g -DDEVTIME -I/usr/local/Wt-Debug/include -I/usr/include/gpgme++ -MMD -MP -MF "$@.d" -o ${OBJECTDIR}/PopupExpiryTime.o PopupExpiryTime.cpp
 
+${OBJECTDIR}/PopupExportSecretKey.o: PopupExportSecretKey.cpp
+	${MKDIR} -p ${OBJECTDIR}
+	${RM} "$@.d"
+	$(COMPILE.cc) -g -DDEVTIME -I/usr/local/Wt-Debug/include -I/usr/include/gpgme++ -MMD -MP -MF "$@.d" -o ${OBJECTDIR}/PopupExportSecretKey.o PopupExportSecretKey.cpp
+
 ${OBJECTDIR}/PopupUploader.o: PopupUploader.cpp
 	${MKDIR} -p ${OBJECTDIR}
 	${RM} "$@.d"