manual: skip build when perl is unavailable

Do not try to generate the manual when perl is unavailable.  This
matches the behavior when makeinfo is unavailable.  Otherwise the
install step fails when trying to generate the libm section since
it runs a perl script.

(cherry picked from commit 1695cdae065fa3693e7b18169a100f53444eac69)

diff --git a/manual/Makefile b/manual/Makefile
index 53822082e2f5a5749555a24561043a55ec1041de..cdb6763e9b72c40a825f4ab7cc8e667e2f966ce4 100644 (file)
--- a/manual/Makefile
+++ b/manual/Makefile
@@ -172,6 +172,8 @@ include ../Rules
 
 .PHONY: install subdir_install install-data
 install-data subdir_install: install
+# libm-err.texi generation requires perl.
+ifneq ($(PERL),no)
 ifneq ($(strip $(MAKEINFO)),:)
 install: $(inst_infodir)/libc.info
        @if $(SHELL) -c '$(INSTALL_INFO) --version' >/dev/null 2>&1; then \
@@ -179,6 +181,7 @@ install: $(inst_infodir)/libc.info
         $(INSTALL_INFO) --info-dir=$(inst_infodir) $(inst_infodir)/libc.info;\
        else : ; fi
 endif
+endif
 # Catchall implicit rule for other installation targets from the parent.
 install-%: ;