[gmime] Bump the minimum gpgme requirement to 1.6.0 for gpgme_set_offline

[Jeffrey Stedfast <fejj src gnome org>]

commit fe7df0c14183722ea0c14b5c9834dc67c29135d9
Author: Jeffrey Stedfast <jestedfa microsoft com>
Date:   Sun May 20 11:04:34 2018 -0400

    Bump the minimum gpgme requirement to 1.6.0 for gpgme_set_offline

 README.md    |    2 +-
 configure.ac |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/README.md b/README.md
index 7493a52..c0dcc80 100644
--- a/README.md
+++ b/README.md
@@ -80,7 +80,7 @@ The following packages are RECOMMENDED:
     Domain Names. Libidn2 sources may be obtained from:
       https://www.gnu.org/software/libidn/#downloading
 
-  - GPGME >= 1.8.0 (will build with 1.2.0, but will be missing some functionality)
+  - GPGME >= 1.8.0 (will build with 1.6.0, but will be missing some functionality)
 
     GPGME (GnuPG Made Easy) provides high-level crypto APIs needed for
     encryption, decryption, signing and signature verification for both
diff --git a/configure.ac b/configure.ac
index 32feecf..83dac94 100644
--- a/configure.ac
+++ b/configure.ac
@@ -501,7 +501,7 @@ AC_ARG_ENABLE([crypto],
 
 m4_ifdef([AM_PATH_GPGME_PTHREAD], [
 AS_IF([test "x$enable_crypto" = "xyes"], [
-   AM_PATH_GPGME_PTHREAD(1.2.0, enable_crypto="yes (via GpgME)", enable_crypto="no")
+   AM_PATH_GPGME_PTHREAD(1.6.0, enable_crypto="yes (via GpgME)", enable_crypto="no")
    if test "x$enable_crypto" != "xno"; then
       AC_DEFINE(ENABLE_CRYPTO, 1, [Define if GMime should enable GpgME PGP and S/MIME support.])
    fi