Add FreeBSD CI test

.github/workflows/build.yml

@@ -113,3 +113,25 @@ jobs:
       run: make check
     - name: make distcheck
       run: make distcheck
+  freebsd-openssl:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v4
+    - name: FreeBSD VM build
+      id: test
+      uses: vmactions/freebsd-vm@v1
+      with:
+        usesh: true
+        prepare: |
+          set -x
+          pkg install -y automake fltk
+        run: |
+          set -x
+          pwd
+          freebsd-version
+          ./autogen.sh
+          ./configure
+          cat config.log
+          make
+          make check
+          make distcheck

configure.ac

@@ -143,16 +143,6 @@ dnl -----------------------------------------------------------------
 dnl
 BASE_CUR_WORKING_DIR=`pwd`
 
-dnl --------------------------------------
-dnl Check whether to add /usr/local or not
-dnl (this is somewhat a religious problem)
-dnl --------------------------------------
-dnl
-if test "`$CPP -v < /dev/null 2>&1 | grep '/usr/local/include' 2>&1`" = ""; then
-  CPPFLAGS="$CPPFLAGS -I/usr/local/include"
-  LDFLAGS="$LDFLAGS -L/usr/local/lib"
-fi
-
 dnl ------------------------------------
 dnl Check for socket libs (AIX, Solaris)
 dnl ------------------------------------
@@ -437,13 +427,20 @@ fi
 AM_CONDITIONAL([USE_OPENSSL],  [test "x$openssl_ok" = "xyes"])
 AM_CONDITIONAL([USE_MBEDTLS],  [test "x$mbedtls_ok" = "xyes"])
 
-dnl --------------------------------------------------------------
-dnl Test for iconv functionality in libc or for libiconv usability
-dnl --------------------------------------------------------------
+dnl ----------------------------------------------------------------
+dnl Test for iconv implementation first in libiconv and then in libc
+dnl ----------------------------------------------------------------
 AC_CHECK_HEADER(iconv.h, iconv_ok=yes, iconv_ok=no)
 if test "x$iconv_ok" = "xyes"; then
-  AC_CHECK_LIB(c, iconv_open, LIBICONV_LIBS="",
-    AC_CHECK_LIB(iconv, iconv_open, LIBICONV_LIBS="-liconv", iconv_ok=no))
+  dnl First try to link with the libiconv library if available, otherwise
+  dnl fall back to the implementation of libc. It is required to be done
+  dnl in this order because FreeBSD distributes libiconv headers in
+  dnl /usr/include/local/iconv.h, in the same place the headers for FLTK
+  dnl are placed. If we select to link with libc, the headers provided by
+  dnl libiconv will be used while linking with libc. This causes a linkage
+  dnl error.
+  AC_CHECK_LIB(iconv, iconv_open, LIBICONV_LIBS="-liconv",
+    AC_CHECK_LIB(c, iconv_open, LIBICONV_LIBS="", iconv_ok=no))
 fi
 if test "x$iconv_ok" = "xno"; then
   dnl Test for OpenBSD