libc/uClibc: apply the threading model to the configuration

The threading model shall be be set in the .config file.
Also, offer the choice between 'old/stable' and 'new' linuxthreads.

config/libc/uClibc.in.2

@@ -0,0 +1,36 @@
+# uClibc second-part option
+
+if THREADS_LINUXTHREADS
+
+choice
+    bool
+    prompt "Linuxthread implementation: "
+    default LIBC_UCLIBC_LNXTHRD_OLD
+
+config LIBC_UCLIBC_LNXTHRD_OLD
+    bool
+    prompt "old/stable"
+    help
+      From the uClibc config option help:
+        There are two versions of linuxthreads.  The older (stable) version
+        has been in uClibc for quite a long time but hasn't seen too many
+        updates other than bugfixes.
+
+config LIBC_UCLIBC_LNXTHRD_NEW
+    bool
+    prompt "new"
+    help
+      From the uClibc config option help:
+        The new version has not been tested much, and lacks ports for arches
+        which glibc does not support (like bfin/frv/etc...), but is based on
+        the latest code from glibc, so it may be the only choice for the
+        newer ports (like alpha/amd64/64bit arches and hppa).
+
+endchoice
+
+config LIBC_UCLIBC_LNXTHRD
+    string
+    default "old"   if LIBC_UCLIBC_LNXTHRD_OLD
+    default "new"   if LIBC_UCLIBC_LNXTHRD_NEW
+
+endif # THREADS_LINUXTHREADS

scripts/build/libc/uClibc.sh

@@ -327,6 +327,36 @@ mungeuClibcConfig() {
 			ENDSED
     fi
 
+    # Push the threading model
+    # Note: we take into account all of the .28, .29, .30 and .31
+    #       versions, here.
+    case "${CT_THREADS}:${CT_LIBC_UCLIBC_LNXTHRD}" in
+        none:*)
+            cat <<-ENDSED
+				s/^# HAS_NO_THREADS is not set/HAS_NO_THREADS=y/
+				s/^UCLIBC_HAS_THREADS=y/# UCLIBC_HAS_THREADS is not set/
+				s/^LINUXTHREADS_OLD=y/# LINUXTHREADS_OLD is not set/
+				s/^LINUXTHREADS_NEW=y/# LINUXTHREADS_NEW is not set/
+				ENDSED
+            ;;
+        *:old)
+            cat <<-ENDSED
+				s/^HAS_NO_THREADS=y/# HAS_NO_THREADS is not set/
+				s/^# UCLIBC_HAS_THREADS is not set/UCLIBC_HAS_THREADS=y/
+				s/^# LINUXTHREADS_OLD is not set/# LINUXTHREADS_OLD=y/
+				s/^LINUXTHREADS_NEW=y/# LINUXTHREADS_NEW is not set/
+				ENDSED
+            ;;
+        *:new)
+            cat <<-ENDSED
+				s/^# HAS_NO_THREADS is not set/HAS_NO_THREADS=y/
+				s/^# UCLIBC_HAS_THREADS is not set/UCLIBC_HAS_THREADS=y/
+				s/^LINUXTHREADS_OLD=y/# LINUXTHREADS_OLD is not set/
+				s/^# LINUXTHREADS_NEW is not set/# LINUXTHREADS_NEW=y/
+				ENDSED
+            ;;
+    esac
+
     # Always build the libpthread_db
     cat <<-ENDSED
 		s/^# PTHREADS_DEBUG_SUPPORT is not set.*/PTHREADS_DEBUG_SUPPORT=y/