glib: bump min required glib library version to 2.48

Per supported platforms doc[1], the various min glib on relevant distros is:

  RHEL-8: 2.56.1
  RHEL-7: 2.50.3
  Debian (Buster): 2.58.3
  Debian (Stretch): 2.50.3
  OpenBSD (Ports): 2.58.3
  FreeBSD (Ports): 2.56.3
  OpenSUSE Leap 15: 2.54.3
  SLE12-SP2: 2.48.2
  Ubuntu (Xenial): 2.48.0
  macOS (Homebrew): 2.56.0

This suggests that a minimum glib of 2.48 is a reasonable target.

Compared to the previous version bump in

  commit e7b3af81
  Author: Daniel P. Berrangé <berrange@redhat.com>
  Date:   Fri May 4 15:34:46 2018 +0100

    glib: bump min required glib library version to 2.40

This will result in us dropping support for Debian Jessie and
Ubuntu 14.04.

As per the commit message 14.04 was already outside our list
of supported build platforms and an exception was only made
because one of the build hosts used during merge testing was
stuck on 14.04.

Debian Jessie is justified to drop because we only aim to
support at most 2 major versions of Debian at any time. This
means Buster and Stretch at this time.

The g_strv_contains compat code is dropped as this API is
present since 2.44

The g_assert_cmpmem compat code is dropped as this API is
present since 2.46

[1] https://qemu.weilnetz.de/doc/qemu-doc.html#Supported-build-platformsReviewed-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: NStefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

configure

@@ -3636,7 +3636,7 @@ fi
 ##########################################
 # glib support probe
 
-glib_req_ver=2.40
+glib_req_ver=2.48
 glib_modules=gthread-2.0
 if test "$modules" = yes; then
     glib_modules="$glib_modules gmodule-export-2.0"

crypto/hmac-glib.c

@@ -21,12 +21,7 @@ static int qcrypto_hmac_alg_map[QCRYPTO_HASH_ALG__MAX] = {
     [QCRYPTO_HASH_ALG_MD5] = G_CHECKSUM_MD5,
     [QCRYPTO_HASH_ALG_SHA1] = G_CHECKSUM_SHA1,
     [QCRYPTO_HASH_ALG_SHA256] = G_CHECKSUM_SHA256,
-/* Support for HMAC SHA-512 in GLib 2.42 */
-#if GLIB_CHECK_VERSION(2, 42, 0)
     [QCRYPTO_HASH_ALG_SHA512] = G_CHECKSUM_SHA512,
-#else
-    [QCRYPTO_HASH_ALG_SHA512] = -1,
-#endif
     [QCRYPTO_HASH_ALG_SHA224] = -1,
     [QCRYPTO_HASH_ALG_SHA384] = -1,
     [QCRYPTO_HASH_ALG_RIPEMD160] = -1,

include/glib-compat.h

@@ -19,12 +19,12 @@
 /* Ask for warnings for anything that was marked deprecated in
  * the defined version, or before. It is a candidate for rewrite.
  */
-#define GLIB_VERSION_MIN_REQUIRED GLIB_VERSION_2_40
+#define GLIB_VERSION_MIN_REQUIRED GLIB_VERSION_2_48
 
 /* Ask for warnings if code tries to use function that did not
  * exist in the defined version. These risk breaking builds
  */
-#define GLIB_VERSION_MAX_ALLOWED GLIB_VERSION_2_40
+#define GLIB_VERSION_MAX_ALLOWED GLIB_VERSION_2_48
 
 #pragma GCC diagnostic push
 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
@@ -63,26 +63,6 @@
  * without generating warnings.
  */
 
-static inline gboolean g_strv_contains_qemu(const gchar *const *strv,
-                                            const gchar *str)
-{
-#if GLIB_CHECK_VERSION(2, 44, 0)
-    return g_strv_contains(strv, str);
-#else
-    g_return_val_if_fail(strv != NULL, FALSE);
-    g_return_val_if_fail(str != NULL, FALSE);
-
-    for (; *strv != NULL; strv++) {
-        if (g_str_equal(str, *strv)) {
-            return TRUE;
-        }
-    }
-
-    return FALSE;
-#endif
-}
-#define g_strv_contains(a, b) g_strv_contains_qemu(a, b)
-
 #if defined(_WIN32) && !GLIB_CHECK_VERSION(2, 50, 0)
 /*
  * g_poll has a problem on Windows when using
@@ -92,24 +72,6 @@ static inline gboolean g_strv_contains_qemu(const gchar *const *strv,
 gint g_poll_fixed(GPollFD *fds, guint nfds, gint timeout);
 #endif
 
-
-#ifndef g_assert_cmpmem
-#define g_assert_cmpmem(m1, l1, m2, l2)                                        \
-    do {                                                                       \
-        gconstpointer __m1 = m1, __m2 = m2;                                    \
-        int __l1 = l1, __l2 = l2;                                              \
-        if (__l1 != __l2) {                                                    \
-            g_assertion_message_cmpnum(                                        \
-                G_LOG_DOMAIN, __FILE__, __LINE__, G_STRFUNC,                   \
-                #l1 " (len(" #m1 ")) == " #l2 " (len(" #m2 "))", __l1, "==",   \
-                __l2, 'i');                                                    \
-        } else if (memcmp(__m1, __m2, __l1) != 0) {                            \
-            g_assertion_message(G_LOG_DOMAIN, __FILE__, __LINE__, G_STRFUNC,   \
-                                "assertion failed (" #m1 " == " #m2 ")");      \
-        }                                                                      \
-    } while (0)
-#endif
-
 #pragma GCC diagnostic pop
 
 #endif