gdb: Allow more control over where to find python libraries

The motivation behind this commit is to make it easier to bundle the
Python *.py library files with GDB when statically linking GDB against
libpython.  The Python files will be manually added into the GDB
installation tree, and GDB should be able to find them at run-time.
The installation tree will look like this:

  .
  |-- bin/
  |-- include/
  |-- lib/
  |   `-- python3.8/
  `-- share/

The benefit here is that the entire installation tree can be bundled
into a single archive and copied to another machine with a different
version of Python installed, and GDB will still work, including its
Python support.

In use the new configure options would be used something like this,
first build and install a static Python library:

  mkdir python
  cd python
  # Clone or download Python into a src/ directory.
  mkdir build
  export PYTHON_INSTALL_PATH=$PWD/install
  cd build
  ../src/configure --disable-shared --prefix=$PYTHON_INSTALL_PATH
  make
  make install

Now build and install GDB:

  mkdir binutils-gdb
  cd binutils-gdb
  # Clone or download GDB into a src/ directory.
  mkdir build
  export GDB_INSTALL_DIR=$PWD/install
  cd build
  ../src/configure \
      --prefix=$GDB_INSTALL_DIR \
      --with-python=$PYTHON_INSTALL_PATH/bin/python3 \
      --with-python-libdir=$GDB_INSTALL_DIR/lib
  make all-gdb
  make install-gdb

Finally, copy the Python libraries into the GDB install:

  cp -r $PYTHON_INSTALL_DIR/lib/python3.8/ $GDB_INSTALL_DIR/lib

After this the Python src, build, and install directories are no
longer needed and can be deleted.

If the new --with-python-libdir option is not used then the existing
behaviour is left unchanged, GDB will look for the Python libraries in
the lib/ directory within the python path.  The concatenation of the
python prefix and the string 'lib/' is now done at configure time,
rather than at run time in GDB as it was previous, however, this was
never something that the user had dynamic control over, so there's no
loss of functionality.

gdb/ChangeLog:

	* config.in: Regenerate.
	* configure: Regenerate.
	* configure.ac: Add --with-python-libdir option.
	* main.c: Use WITH_PYTHON_LIBDIR.

1 files changed, 49 insertions, 0 deletions

diff --git a/gdb/configure b/gdb/configure
index 2f6ecb5..e6b5a51 100755
--- a/gdb/configure
+++ b/gdb/configure
@@ -890,6 +890,7 @@ with_mpfr
 with_libmpfr_prefix
 with_libmpfr_type
 with_python
+with_python_libdir
 with_guile
 enable_source_highlight
 with_intel_pt
@@ -1625,6 +1626,8 @@ Optional Packages:
   --with-libmpfr-type=TYPE     type of library to search for (auto/static/shared)
   --with-python[=PYTHON]  include python support
                           (auto/yes/no/<python-program>)
+  --with-python-libdir[=DIR]
+                          search for python's libraries in DIR
   --with-guile[=GUILE]    include guile support
                           (auto/yes/no/<guile-version>/<pkg-config-program>)
   --with-intel-pt         include Intel Processor Trace support (auto/yes/no)
@@ -10665,6 +10668,21 @@ _ACEOF
   fi
 fi
 
+
+# Check whether --with-python-libdir was given.
+if test "${with_python_libdir+set}" = set; then :
+  withval=$with_python_libdir;
+else
+
+    # If no python libdir is specified then select one based on
+    # python's prefix path.
+    if test -n "${python_prefix}"; then
+      with_python_libdir=${python_prefix}/lib
+    fi
+
+fi
+
+
 if test "${have_libpython}" != no; then
 
 $as_echo "#define HAVE_PYTHON 1" >>confdefs.h
@@ -10675,6 +10693,37 @@ $as_echo "#define HAVE_PYTHON 1" >>confdefs.h
   CONFIG_INSTALL="$CONFIG_INSTALL install-python"
   ENABLE_CFLAGS="$ENABLE_CFLAGS \$(SUBDIR_PYTHON_CFLAGS)"
 
+  if test -n "${with_python_libdir}"; then
+
+cat >>confdefs.h <<_ACEOF
+#define WITH_PYTHON_LIBDIR "${with_python_libdir}"
+_ACEOF
+
+
+  if test "x$exec_prefix" = xNONE || test "x$exec_prefix" = 'x${prefix}'; then
+     if test "x$prefix" = xNONE; then
+     	test_prefix=/usr/local
+     else
+	test_prefix=$prefix
+     fi
+  else
+     test_prefix=$exec_prefix
+  fi
+  value=0
+  case ${with_python_libdir} in
+     "${test_prefix}"|"${test_prefix}/"*|\
+	'${exec_prefix}'|'${exec_prefix}/'*)
+     value=1
+     ;;
+  esac
+
+cat >>confdefs.h <<_ACEOF
+#define PYTHON_LIBDIR_RELOCATABLE $value
+_ACEOF
+
+
+  fi
+
   # Flags needed to compile Python code (taken from python-config --cflags).
   # We cannot call python-config directly because it will output whatever was
   # used when compiling the Python interpreter itself, including flags which