subprojects: Prepare for release

The Vala README only mentions autotools instructions, and when Vala is
compiled that way the -frida suffix is not added to the version string,
and the frida-core check for Vala fails.

Therefore, clarify that Vala needs to be built from source with Meson.

meson.build

@@ -12,9 +12,11 @@ if not meson.get_compiler('vala').version().endswith('-frida')
   error('''Incompatible Vala compiler detected.
 
 Frida currently relies on features not yet upstream. Grab the Frida-optimized
-Vala compiler from:
+Vala sources from:
 
-    https://github.com/frida/vala''')
+    https://github.com/frida/vala
+
+and compile them with Meson.''')
 endif
 
 c_languages = ['c', 'cpp']
@@ -269,12 +271,14 @@ if host_os == 'linux'
 #endif
 '''
   if cc.compiles(glibc_src, name: 'compiling for glibc')
-    cdata.set('HAVE_GLIBC', 1)
+    libc = 'glibc'
   elif cc.compiles(uclibc_src, name: 'compiling for uClibc')
-    cdata.set('HAVE_UCLIBC', 1)
+    libc = 'uclibc'
   else
-    cdata.set('HAVE_MUSL', 1)
+    libc = 'musl'
   endif
+  cdata.set('HAVE_' + libc.to_upper(), 1)
+  vala_flags += '--define=' + libc.to_upper()
 endif
 
 if get_option('b_sanitize') == 'address'

subprojects/frida-gum.wrap

@@ -1,6 +1,6 @@
 [wrap-git]
 url = https://github.com/frida/frida-gum.git
-revision = 17.2.6
+revision = 17.2.7
 depth = 1
 
 [provide]