Revert gperf: remove

gperf is a basic tool used when building packages. It's not available on
all hosts, in which case having a host package like this one is
required. For instance the CircleCI environment does not contain gperf,
in which case building of software requiring gperf fails.

This commit reverts the gperf removal.

Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>

libs/gperf/patches/100-include_own_first.patch

@@ -0,0 +1,26 @@
+diff --git a/lib/Makefile.in b/lib/Makefile.in
+index 29bbf92..cf2bf3c 100644
+--- a/lib/Makefile.in
++++ b/lib/Makefile.in
+@@ -61,7 +61,7 @@ SHELL = /bin/sh
+ VPATH = $(srcdir)
+ 
+ OBJECTS  = getopt.$(OBJEXT) getopt1.$(OBJEXT) getline.$(OBJEXT) hash.$(OBJEXT)
+-CPPFLAGS = @CPPFLAGS@ -I$(srcdir)
++CPPFLAGS = -I$(srcdir) @CPPFLAGS@
+ 
+ TARGETLIB = libgp.a
+ 
+diff --git a/src/Makefile.in b/src/Makefile.in
+index 6866ffd..bd4df14 100644
+--- a/src/Makefile.in
++++ b/src/Makefile.in
+@@ -64,7 +64,7 @@ VPATH = $(srcdir)
+ OBJECTS  = version.$(OBJEXT) positions.$(OBJEXT) options.$(OBJEXT) keyword.$(OBJEXT) keyword-list.$(OBJEXT) \
+            input.$(OBJEXT) bool-array.$(OBJEXT) hash-table.$(OBJEXT) search.$(OBJEXT) output.$(OBJEXT) main.$(OBJEXT)
+ LIBS     = ../lib/libgp.a @GPERF_LIBM@
+-CPPFLAGS = @CPPFLAGS@ -I. -I$(srcdir)/../lib
++CPPFLAGS = -I. -I$(srcdir)/../lib @CPPFLAGS@
+ 
+ TARGETPROG = gperf$(EXEEXT)
+