Merge branch 'rj/build-tweaks'

Various build tweaks, including CSPRNG selection on some platforms.

* rj/build-tweaks:
  config.mak.uname: set CSPRNG_METHOD to getrandom on Linux
  config.mak.uname: add arc4random to the cygwin build
  config.mak.uname: add sysinfo() configuration for cygwin
  builtin/gc.c: correct RAM calculation when using sysinfo
  config.mak.uname: add clock_gettime() to the cygwin build
  config.mak.uname: add HAVE_GETDELIM to the cygwin section
  config.mak.uname: only set NO_REGEX on cygwin for v1.7
  config.mak.uname: add a note about NO_STRLCPY for Linux
  Makefile: remove NEEDS_LIBRT build variable
  meson.build: set default help format to html on windows
  meson.build: only set build variables for non-default values
  Makefile: only set some BASIC_CFLAGS when RUNTIME_PREFIX is set
  meson.build: remove -DCURL_DISABLE_TYPECHECK

meson.build

@@ -727,10 +727,7 @@ endif
 # These variables are used for building libgit.a.
 libgit_c_args = [
   '-DBINDIR="' + get_option('bindir') + '"',
-  '-DDEFAULT_EDITOR="' + get_option('default_editor') + '"',
   '-DDEFAULT_GIT_TEMPLATE_DIR="' + get_option('datadir') / 'git-core/templates' + '"',
-  '-DDEFAULT_HELP_FORMAT="' + get_option('default_help_format') + '"',
-  '-DDEFAULT_PAGER="' + get_option('default_pager') + '"',
   '-DETC_GITATTRIBUTES="' + get_option('gitattributes') + '"',
   '-DETC_GITCONFIG="' + get_option('gitconfig') + '"',
   '-DFALLBACK_RUNTIME_PREFIX="' + get_option('prefix') + '"',
@@ -742,6 +739,29 @@ libgit_c_args = [
   '-DPAGER_ENV="' + get_option('pager_environment') + '"',
   '-DSHELL_PATH="' + fs.as_posix(target_shell.full_path()) + '"',
 ]
+
+editor_opt = get_option('default_editor')
+if editor_opt != '' and editor_opt != 'vi'
+  libgit_c_args += '-DDEFAULT_EDITOR="' + editor_opt + '"'
+endif
+
+pager_opt = get_option('default_pager')
+if pager_opt != '' and pager_opt != 'less'
+  libgit_c_args += '-DDEFAULT_PAGER="' + pager_opt + '"'
+endif
+
+help_format_opt = get_option('default_help_format')
+if help_format_opt == 'platform'
+  if host_machine.system() == 'windows'
+    help_format_opt = 'html'
+  else
+    help_format_opt = 'man'
+  endif
+endif
+if help_format_opt != 'man'
+    libgit_c_args += '-DDEFAULT_HELP_FORMAT="' + help_format_opt + '"'
+endif
+
 libgit_include_directories = [ '.' ]
 libgit_dependencies = [ ]
 
@@ -1012,7 +1032,6 @@ if curl.found()
   # Most executables don't have to link against libcurl, but we still need its
   # include directories so that we can resolve LIBCURL_VERSION in "help.c".
   libgit_dependencies += curl.partial_dependency(includes: true)
-  libgit_c_args += '-DCURL_DISABLE_TYPECHECK'
   build_options_config.set('NO_CURL', '')
 else
   libgit_c_args += '-DNO_CURL'