adds patches required to build hdf5 1.8.10 (#7386)

For hdf5 `1.8.10` and some compilers, the hdf5 build system adds the
'-ansi' flag. hdf5 1.8.10 is not actually ansi compliant so this
adds a patch to modify the places where it violates ansi
compatibility (which ends up being a few comments).

var/spack/repos/builtin/packages/hdf5/package.py

@@ -50,6 +50,7 @@ class Hdf5(AutotoolsPackage):
     version('1.8.14', 'a482686e733514a51cde12d6fe5c5d95')
     version('1.8.13', 'c03426e9e77d7766944654280b467289')
     version('1.8.12', 'd804802feb99b87fc668a90e6fa34411')
+    version('1.8.10', '710aa9fb61a51d61a7e2c09bf0052157')
 
     variant('debug', default=False,
             description='Builds a debug version of the library')
@@ -97,6 +98,18 @@ class Hdf5(AutotoolsPackage):
     patch('h5f90global-mult-obj-same-equivalence-same-common-block.patch',
           when='@1.10.1%intel@18')
 
+    # Turn line comments into block comments to conform with pre-C99 language
+    # standards. Versions of hdf5 after 1.8.10 don't require this patch,
+    # either because they conform to pre-C99 or neglect to ask for pre-C99
+    # language standards from their compiler. The hdf5 build system adds
+    # the -ansi cflag (run 'man gcc' for info on -ansi) for some versions
+    # of some compilers (see hdf5-1.8.10/config/gnu-flags). The hdf5 build
+    # system does not provide an option to disable -ansi, but since the
+    # pre-C99 code is restricted to just five lines of line comments in
+    # three src files, this patch accomplishes the simple task of patching the
+    # three src files and leaves the hdf5 build system alone.
+    patch('pre-c99-comments.patch', when='@1.8.10')
+
     filter_compiler_wrappers('h5cc', 'h5c++', 'h5fc', relative_root='bin')
 
     def url_for_version(self, version):

var/spack/repos/builtin/packages/hdf5/pre-c99-comments.patch

@@ -0,0 +1,43 @@
+diff --git a/test/th5s.c b/test/th5s.c
+index 462bc36..8e18fad 100644
+--- a/test/th5s.c
++++ b/test/th5s.c
+@@ -730,8 +730,8 @@ test_h5s_zero_dim(void)
+         ret = H5Pset_chunk(plist_id, SPACE1_RANK, chunk_dims);
+         CHECK(ret, FAIL, "H5Pset_chunk");
+ 
+-        // ret = H5Pset_alloc_time(plist_id, alloc_time);
+-        // CHECK(ret, FAIL, "H5Pset_alloc_time");
++        /* ret = H5Pset_alloc_time(plist_id, alloc_time); */
++        /* CHECK(ret, FAIL, "H5Pset_alloc_time"); */
+ 
+         dset1 = H5Dcreate2(fid1, BASICDATASET1, H5T_NATIVE_INT, sid_chunk, H5P_DEFAULT, plist_id, H5P_DEFAULT);
+         CHECK(dset1, FAIL, "H5Dcreate2");
+diff --git a/tools/h5dump/h5dump_ddl.c b/tools/h5dump/h5dump_ddl.c
+index ee6de5e..3ed6045 100644
+--- a/tools/h5dump/h5dump_ddl.c
++++ b/tools/h5dump/h5dump_ddl.c
+@@ -1341,8 +1341,8 @@ handle_attributes(hid_t fid, const char *attr, void UNUSED * data, int UNUSED pe
+     string_dataformat.do_escape = display_escape;
+     outputformat = &string_dataformat;
+ 
+-    //attr_name = attr + j + 1;
+-	// need to replace escape characters
++    /* attr_name = attr + j + 1; */
++	/* need to replace escape characters */
+ 	attr_name = h5tools_str_replace(attr + j + 1, "\\/", "/");
+ 
+ 
+diff --git a/tools/lib/h5tools_str.c b/tools/lib/h5tools_str.c
+index 9ce3524..3b4e5e7 100644
+--- a/tools/lib/h5tools_str.c
++++ b/tools/lib/h5tools_str.c
+@@ -632,7 +632,7 @@ h5tools_str_indent(h5tools_str_t *str, const h5tool_format_t *info,
+         h5tools_str_append(str, "%s", OPT(info->line_indent, ""));
+     }
+ 
+-//    ctx->need_prefix = 0;
++/*    ctx->need_prefix = 0; */
+ }
+ 
+ /*-------------------------------------------------------------------------